i don't understand why your friend would want to look for this, when there is such a fantastic world of b/j shipping out there. she can't see the chemistry because it's not there.
i actually know nothing b/m shippers, because i run the other way from them...so i'm about to talk completely out of my ass.
i would like to repeat, this theory is completely out of my ass.
my theory is that b/m shippers don't care for justin, the character, or the actor, or both, for whatever reason. but they liked michael straight away. and identified with his unrequited lust love for brian. so they saw what they wanted to see. chemistry that doesn't really exist. they took michael's understandable lust and love, and brian's caring friendship, and turned it into more then what it was for to suit their own needs and desires. this is the only way i can explain b/m.
because i don't know how you can see justin and brian on screen together and not see the chemistry, other then if you don't want to see it. even when they aren't together, in fact almost more so when they aren't together, it is there. (this is why i crazily love and adore episode 302-307, omg the chemistry)
so again, i don't know anything about b/m shippers, i don't think i even know any, but this is the only way i can explain their existance in my own head.