How about this - when an ooze is first generated on a level, it has a cloning counter with effect akin to DNA telomeres. Each cloning decrements the counter of those produced, and when an ooze has counter at zero it cannot clone.
If the current settings for cloning are felt to be okay (maybe I just don't have the knack

) then it would still be worthwhile to have such a counter, with an initial setting which allows for generation of a large enough crowd to punish the careless ooze murderer. It would avoid having showstoppers created by a duration/area effect - once Mt Doom became unreachable because of brittle oozes on a level which approaches it, the game turns simply became too long in real time. Okay, being dumb enough to set a load of the most promiscuous little gits on fire should be punished, but that's a bit much.
Say it started at 8, the most ham-fisted oozophobe would end up with 2(7), 4(6), 8(5) - - 256(0, no more cloning). So nobody's quite that poor at ooze assassination, but a more likely 50-100 of the things should be sufficient to function as a "wish I'd never started this" crowd.