I don't think people are saying he raped him just yet. What people are worried about is the next chapter. He has him naked on the bed and is biting and licking him while he's unconscious. That is considered sexual assault because he didn't consent to be stripped and touched in that way (even if they were in a previous relationship). The signs are there that this could potentially lead to him raping him, which is why people are afraid

AAAAAA I WAS SO SCARED AT THE BEGINNING CAUSE OF THE NOTICE
but it’s chill now
Also I think people need to look at the last panel again cause Aaron didn’t rape him ( look at the hole ) (=・ω・=)just bit him and stuff which obviously isn’t the best but it’s massively different from rape