PS beer is not necessarily an acquired taste. I liked beer the first time I tried it. Dunno if it's been mentioned, but I think a medium bodied beer like Michelob Ultra would be good as a starting point. Depending on how he feels about it, you can go lighter or darker to suit his tastes. Regardless, everyone who drinks beer goes through their own "feeling out" process where they try different drinks and decide what they do and do not like. Here's an idea: why not just let the kid pick one randomly off the shelf? Rather than try to push beer on him, encourage him to experiment until he finds one he likes.
Also I agree Natty Ice is an abomination, but I think Schlitz and Beast (Milwaukee's Best) Light are worse. That's my opinion though.