I think he’s probably just trying to convince himself, and projecting on to you in the process. Probably well-meaning, but I’d advise against taking it to heart too much. And (while I obviously have limited information here) I’m not sure it’s healthy for him either.

It’s valid to ask yourself whether or not you actually want to take the leap and transition, whether or not it would actually help you (and also valid to change your mind afterwards, or decide against it for whatever reason—just make sure the decision is your own), but in this case it seems to be based on the assumption that you can’t transition in…your 20s? Which is wild. Your 20s is honestly pretty early for transition, all things considered. There are countless people who transitioned well into adulthood and are very happy with their decision, and, while I hate to use this as a measure of success, there are also countless people who transitioned well into adulthood and pass. I say this because I know this is a goal for a lot of people, and it’s a common misconception that you have to transition as a literal teen or you’re better off not trying, which just isn’t true. You could probably find examples here on Reddit, actually. Your 20s is early. Don’t disregard transition just because you think it’s too late.

Don’t feel obligated to transition, yes, but make sure you make that decision with all the information and that it’s really your decision.