At 18/19, there's nothing to learn in the CHL except for bad habits.
NCAA might have been a decent avenue for him if he landed on a good team with a good coach, but Liiga is much better than the CHL at this point.
This is so false. There are countless examples of players who played CHL at 18/19 and went on to become NHL stars or very good players.
If the player can only take bad habits at this age, it is on them. I've seen it with my own eyes when very good players improve at those ages. Drouin came back to the CHL at 18 and did as you said and learned bad habits. Ehlers came back and made it his mission to be a dominate the league and be a 200 ft player. He was already a top 10 pick before that season and he wasn't too good to play in the league. Players can always improve.
I think there may be some importance to play top mins, all situations etc and be relied upon as a top player in the development of prospects. I certainly don't think he is anywhere close to good enough to say that there is nothing to learn in the CHL.