What do you folks think about the Friend Zone / beta orbit concept applied to male-male relationships?

I've had two friends that might have perceived themselves to be in my orbit friend zone. I appreciated their platonic friendship but was not interested in a sexual relationship.

Case #1: I dated him briefly but LJBF'd after a month or two because the sex wasn't working out; nevertheless, I did (and do still) care about him very much and would do anything for him ... except have sex. He seemed to accept it (after a time) but others have commented to me at a later point that they thought he was still interested. Fortunately he now has a partner (a real c**t but that's another story for another time) - I'm happy for him that he now has the kind of relationship he wants (not thrilled about his choice).

Case #2: I was never interested in him, ever, and up front made that as clear as I possibly could without making harsh statements about his physique/etc. (but did go as far as saying "I'm not into you that way, you're not my physical type"). We were friends for awhile because we were both in needy spaces (he was coming out after being in the closet and celibate for half a lifetime, and I was recovering from oneitis). I distanced myself when he became more forceful about the sex issue, in a very manipulative way.

What's the best course of action in these situations? Case #2 I don't care that much about (turns out we didn't have much in common after all, the friendship was entirely situational, plus he's terminally a wuss). Case #1 I do care about because I value the friendship, and have fretted over potential mixed messages and what it might be like from his PoV.

TLDR: How do you maintain a platonic friendship when one side wants sex and the other does not?