Microbomb + vuvuzela = BOOM

[DyssalC]

not sure on this one, but even 1 microbomb is enough to remove limbs, right ?

Yes it is, however, consider that the station is literally filled with stuff. Lets say a traitor spends all ten telecrystals on microbombs and implants ten different things with them. Even then the chances are still fairly low of all of them being used, making it so that only about 6-7 are even detonated, more if he's lucky, for some brute and maybe a lost limb.
Or maybe the traitor is procedurally injecting things, like leaving an implanted burn patch or emergency oxygen tank near a hull breach. He does this the whole round and gets ten victims.
Is this not okay? He went around laying smart traps around the station for unsuspecting crew to blow themselves up with. And of course most people who know about this sort of thing or experience it would know to look out for that sort of thing, forcing the traitor to have to play smarter to get more experienced players with it.