I've kissed neg men. Neg men have kissed me.
I've sucked neg dick. Neg dudes have sucked my dick. I've licked neg ass. Neg tongues have eaten my ass.
Rimming, fucking, making out, cuddling, making love--a neg person and a poz person can do all those things safely.
But most men don't know this or don't care. Most HIV-negative gay men treat men HIV-positive gay men like vampires or monsters.