Sounds absurd to me. We were encouraged to stick to fullstops until we had done an hour or two in the circuit post first solo because it is a little frantic when you're a newbie, but a blanket ban?!
FWIW, I would say that it would not be an easy decision for wg100 to go against the perceived wisdom of sticking to one training provider. If he/she is at one of the bigger FTOs, in the dewy eyes of a prospective employer the genuine silliness of this blanket ban might be outweighed by the FTO's overall reputation.