Would a person be considered a homosexual if another person's penis touched their anus through clothing, even if there was no intention or act of sodomy?

It is not permissible to associate with bad company. Attempting to commit an indecency is considered a precursor to evil, not sodomy. Sodomy is penetration into the anus of a male. Regret over what happened is a good sign, and one must seek forgiveness. You did not commit the act of the people of Lot, so do not succumb to the whispers of Satan that call for despair from the mercy of Allah.