Xenophage is perhapse to close to xenobiology and so might be better used for an eater of aliens, not just sapient aliens. On the other hand people tend to have the gyst of what xeno- means whilst sophont- would leave me and most your readers confused.
I had a thread ages ago about the word for sex between different sentient (I should have said saliant) life forms here but it didn’t get far beyonde the idea of xenophilia, xenogamy, and the fact that Larry Niven called it rishathra when between different hominids.