I don’t know how we are going to answer this as a GQ.
We don’t have available to us any current or former Greek catamites to interview. We also don’t (unless someone points me to it) have available anything that would approach scientifically-reliable data collected from the Greek boys at that time.
I suspect that the best a person adducing such a claim would have to adduce would be an account from an old-time Greek discussing just how great the practice was: the men got to enjoy the aesthetic beauty of a young boy, the boy got the benefit of an older man’s knowledge, wisdom, etc. But I’m hardly going to regard that as dispositive, because the old goats writing such apologia were no doubt avid chickenhawks themselves, and that’s precisely the kind of alibi someone would give if he were really motivated by nothing other than lust for someone younger and more powerless than himself.
I will also note that there is no shortage of modern-day examples of such rationalizations, which (correctly) no one ever gives a shred of credence. I could find an article about Paul Shanley, the disgraced priest, in which he was quoted making claims to the effect that “in most cases of such relationships, the child is the aggressor” and “the worst harm is done by revealing the relationship, since it is only the shame and stigma attached by society when a big fuss is made of it that makes it traumatic for a child to have a sexual relationship with an adult.” Of course, these very statements should have been the reddest of flags for his superiors that he was speaking not out of a desire for accurate psychological evaluation of adult-child relations, but out of a wild attempt to justify the rampant rape of boys that he was contemporaneously engaging in.
In any event, it’s almost beside the point to ask, “was it okay for the boys?” The answer depends on how you define “good for the boys” or “damaging,” which means we (as a society) just have to take a normative position on what is “good” for children, and say that this ain’t it. Because you could find instances of kids who, through brainwashing, or bribery, or need for affection, actually did kind of “enjoy” the attention of adults, but we’ve decided that’s not a healthy enjoyment, and the law and policy are pretty comfortable with saying that certain classes of people just don’t have the capacity to give informed consent to what is or is not good for them. That’s why “but she wanted it” is never a defense to sleeping with a jailbait girl. On the flip side, the “hey, in the right setting, it can actually be good for the kid” is pernicious from the mindset of the offender, even if he believes it; it impels predators to rationalize their predation by telling themselves there’s no way their actions can be harmful, even when the evidence of their own eyes should convince them there’s no way it can be true.
I’m not saying the person who made that comment the OP saw about ancient Greece is an incipient molester; I’m merely noting that we can’t know factually how things went back then, but that by the way, many molesters do make such comments.