Well, he could rebind that key too
. The only keys you can't rebind properly are qwer. (Though you can rebind other keys to them, say smartcasting). Not sure why we don't let you rebind them at this time <_<;
As for pathing, it's possibly latency related - I have pretty darn good pathing when I play, but I also play at 8 or 30 ping if I'm at work or home. I would submit a ticket at support.leagueoflegends.com in case this is actually a known issue I don't know about, and if not they'll have QA look into it with our latency generator.