I’m not sure you’d get sued for libel. Legally speaking, any non-penis penatrative sexual assault wouldn’t be rape even if you would call it that in other contexts.

Where I live, rape isn’t actually in the criminal code at all. There is only “criminal sexual misconduct, first degree”, which also includes other terrible things that people can do to each other.

No one gets sued for libel for using the dictionary definition of the word rather than the legal definition outside of a courtroom.