Well, I want to promote healthy aiptasia reproduction

I know that stress may prompt splitting, but this is not really "reproduction" of a growing specimen population. The goal is not just for the nem to split or bud, it is to grow a nice furry rock of aiptasia!
Since aiptasia is much more hearty than the average coral specimen, stressing an aiptasia would kill other corals... if they were in the tank. I don't want to force poor tank conditions because this would not be a "normal" situation for those trying to keep a tank. Afterall, many new hobbyist feed the nems by mistake and other overfeed to provide an abundant food source.
Finally, I am really doubting the reported reproduction rate of these nems. It seems that a single nem (at least this nem) can not turn into a plague as quickly as I initially thought. So I am really going to doubt the other reports of "one" anemone turned into "thousands". I think there were already multiple nems that just were not observed.