i'm flying SFO-DEN-AUS. I'm 1P, and am entitled to 3 checked bags with 70 lbs limit to each that I won't be utilizing for myself. I've got 2 hr layover in DEN. My friend is moving from DEN to AUS and wants me to help him carry some things down to AUS. Can he wait for me at DEN, have me exit security, take his bags, check them in under my name and then I'll continue to AUS with the checked bags? It's mostly some clothes and books that my friend wants me to take.

Is this allowed? wouldn't it be the same as if I exited security, went to a luggage shop quickly, bought 3 bags and then check them onward to AUS even though I didn't check anything on the SFO-DEN leg?