Neat way to launch. Sorta like them old German rocket planes back in the day. Not quite sure that it would be F.A.A. approved but I dont have my private pilots licence so I would not know.
I would however speak to the pilot of that plane and have them seriously check that hinge on the right elevator as that is a lot of rust on a hard point like that and would surely wreck someones day if it were to cut loose mid air.