You can still do curls, and do the big lifts, like 100% of the people he wants to look like do.
In an ideal world, sure. But there’s only so much time in the gym and so much you can throw at the body without impacting recovery. Instead of waisting time and recovery resources on curls, the kid should do a few extra sets of rows, or pull ups, or some other back movement. That’ll hit the biceps plenty while providing extra work for the back.
Except that a set of rows does not have the same recovery demands as a set of curls, so that’s an irrelevant point. Also, very few newbs train too much to recover from (if anything they just undereat).
I fail to see how adding 3 sets of curls at the end of a back workout could possibly impact OP negatively. They should be done last and not first though.