So sea hares are supposed to help out with hair algae. The issue is they have an ink that can cause issues in a tank if not removed promptly (released when stressed or in defense mode). They often will starve in captivity as once the algae is gone they slowly starve out. My plan is to rehome it once my algae is under control.
That said, the eggs are likely infertile as while most are hermaphroditic, it still takes two for fertilization (if I read it correctly). But in aquaria, if the eggs hatch they are unlikely to survive through their plaktonic stage. Due to filters, powerheads and being ate by fish. This is all just based on my research.