I'm not too sure if it is possible to stop him. Even using Goto I've found he would run into melee. Part of the problem is that he has some fairly close range attacks. Another part is he does a lot of aoe, so enemies charge him too. I swear, he thinks he's a prize fighter or something. I guess the real trick is to kill enemies fast, and never let him pick his own target. He's more likely to brawl if you don't order an attack. I think anyway.
"The danger is not that a particular class is unfit to govern. Every class is unfit to govern." Lord Acton
Madam Enigma's History
Unfortunately, I don't have any tips either.
I've just come to terms with the fact that he enjoys dying.
Biggest tip, is also the most dangerous. Try to always keep him close enough to the enforcers to get the +def. That for me (usually) gives me enough time to save his worthless hide. Then again, that also protects the bruiser. That sucker also loves to leave the protective area of your enforcer's maneuvers.
"The danger is not that a particular class is unfit to govern. Every class is unfit to govern." Lord Acton
Madam Enigma's History
I made a thugs\FF mastermind once...got him into the 30's and even then with the redshirt having insane defense he still died a lot (probably due to his level since at that point he's -2 to me, which means he's at least -2 to even cons).
The Porcelain God - DarkKinetics Corruptor
Meat Juice - DarkDarkSoul Brute
Pretty and Strong - Do you really have to ask?
It really depends on your secondary to say what you should do exactly since you can do different things depending on that. I play thugs/dark and I do a few things for example which I will list below.
One of the first things I do which might not be the best for every secondary is to just run right in the middle of the group so that all your thugs are right with you and right next to all the Mobs. Then you don't really need to worry about anyone running off. This only works well I think since my heal is AoE, but doing something like this with other secondaries could still help.
It also seems that after the arsonist has been attacking for a bit he just goes into melee no matter what so I also have my petcom macro setup on num 0 to follow me on defensive which seems to reset them and they come back to me and then I tell them to attack again. I press this when the arsonist is still right next to me to reset his actions and it does really seem to work.
The arsonist is a pain though honestly and only constant attention will keep him alive, but the higher level you get it does get much better. He will still die no doubt about it, but he does die a lot less the higher level you get.
Also sending in your brute first helps also when you get him.
You can also make a macro to call back only your T1 minions instead of all your minions, but I personally don't like to do that. It might work better though if you don't have an AoE heal.
The best thing to do though is just come to terms with the fact the Arsonist is going to die and all you can do is help him die less "sometimes" and hopefully AFTER he has set down his fire patch at least.
"I have always been a fan of science fiction. It all started when my parents forced me to go to church when I was a child."
Your arsonist is a suicidal burning maniac. Learn to love and embrace his short-lived chaos, and rely on your Enforcers to clean up the mess he leaves.
Think of the Arsonist as a troll. Not just any troll mind you, but a flaming, degenerate, unholy monster of a troll, spewing every obscenity possible and doing unorthadox things. Now that random outburst of unitelligable profanity is pretty sweet, as it sets fire to multiple posters in a single setting, especially if they're all grouped together and immobilized by a tpoic. Unfortunately, that little troll will run out of ideas and start hitting in close range against a single poster with a harmless insult, such as "you're gay, lol" or "your avatar sucks, post pad more". The weak, barely demoralizing punch against the single poster arouses the rage of all the other posters (upright or degenerate) onto him. Some, however, will call forth the Moderater and smite your poor little Arsonist.
In short: Flaming Trolls are short lived, as is the little bugger.
Thug Aronist--Speciality--Tanking and alpha taking--ability at primary--nil---ability ay secondry---100% haha.
I must admit, I do think that the AI's for the Bruiser and Arsonist got mixed up right at creation of their programes and that not even the devs have realised this and that any amount of trying to fix this wont mean anything till they realise the initial mistake as its hard wired into them now lol...anyway, jokes aside, he is the most suicidal pet ever...outside of ninjas 
How possible to stop Arsonist from running into Melee? He does not need to anyway; but he just keeps running into melee range to use it almight Brawl!
Any suggestions/tricks that would help him from killing himself and annoying me... :-(
Thanks