Yes he could. The TT would actually have less weight on the TV.
That being said it probably wouldn't tow as nice, but it might if it's setup properly.
There is quite a bit that goes into how well a trailer tows. My 9K 29' TT tows great but the wind resistance on a TT is impressive. For the last two weeks I have been towing a dump trailer with a 7x14' bed at weights around 23-25K GCW and unless it's a decent hill it tows easier than my TT of 4-5K lbs less weight.
My point is weight isn't the only thing that effects how a trailer tows...and probably why the setup in the OP's sig make me cringe. TT's tow much harder than their weight. 5ers flow air better and don't have the same issue.