I just bring my own cloth bag when I go to the grocery store.
But this works too. Actually, it's very cool that he figured that out in his own home -- I wish I had that kind of initiative, to say nothing of my knowledge of science.
The thing is, these bugs already occur in nature - after all, all he did to find them was leave a petri dish lying about. So they can't "get loose" as it were: they're already out there, eating plastic bags. Just really slowly, and in small numbers. What he's done is increase the concentration of the little buggers to useful levels.