One of my players decided to pull a questionable move. He's playing a high STR Fighter, so he figured it would be perfectly reasonable to be able to pick up his medium sized ally as an object interaction and carry him 30 ft. before making his attack. I allowed it at the time because I wasn't sure if it was against the rules and he's an experienced DM, but it seemed pretty fishy and open to abuse. How would you rule this? Is he pulling some shenanigans, or is this kosher?