I think the really relevant ethical question is whether a tulpa has a separate consciousness from its host. From my own researches in the area (which have been very casual, mind you), I consider it highly unlikely that they have separate consciousness, but not so unlikely that I would be willing to create a tulpa and then let it die, for example.

In fact, my uncertainty on this issue is the main reason I am ambivalent about creating a tulpa. It seems like it would be very useful: I solve problems much better when working with other people, even if they don't contribute much; a tulpa more virtuous than myself could be a potent tool for self-improvement; it could help ameliorate the "fear of social isolation" obstacle to potential ambitious projects; I would gain a better understanding of how tulpas work; I could practice dancing and shaking hands more often; etc. etc. But I worry about being responsible for what may be (even with only ~15% subjective probability) a conscious mind, which will then literally die if I don't spend time with it regularly (ref).