Change strange reagent failures

[Mouse]

Used to be how it worked from what I heard. People just ended up abusing it?

If an antag wants to vend monkeys and take all round to make a zombie army, more power to them.

for as long as these zombies don't spread the zombie virus, i see no problem with this.

If it's a regular critter zombie it'll just turn kills into more critter zombies.  Whether that makes an unstoppable army depends on if they aggro monkeys - not all critters seem to do so.