Nitou likes the idea that some science guy who knows what's up is going to try to make good use of the syringe. It cheers him up a little, enough to get a bit of his old bluster back. "Hey, don't worry about me--I've made it this long not worrying about too much about safety!" There's a weak laugh, because it's not like the bluster's magically back in full. "But I'll watch out for myself--you too, man! I'll make sure nothing nasty is hanging around your lab for a while!" He gives Bruce a cheeky wave as he rushes off, looking for some kind of adventure to help him forget what he did to Gary.