Idk bro, I get what you're saying but I think being there for your son physically in his time of need would've been much better for your relationship/his view of you than sending someone else. Yeah it sucks you ""abandoned"" (I can't tell if it was intentional of if his mom kept them apart after the divorce and I don't remember the backstory) him, and (depending on the answer) that hurt will never go away, but you showing that you didn't leave him/are still always there for him would be worlds better than sending someone else. He's still young and there's time to mend the relationship, especially since they both seem to care deeply about each other.
Teenagers are of course fickle (and really, anyone in emotional destress is) so sure, sending the other guy to fetch him first might've been wise, to really make sure he doesn't disappear, bit it does not hurt to visit/make yourself known that you played a part. (Again, long time since I've read, don't remember if dad and son are in contact or haveno contact)