You are missing one point over here, neither your DSO nor USCIS know you used the TPS EAD. There is no way of tracking this. The technical termination is not automatic. It is effective only when known/proved. So just in case, somehow (hopefully not) your DSO/USCIS comes to know of this (again this will not happen automatically) your F-1 status will be deemed to be invalid from the date your used the TPS EAD. So until this happens (and its rare that this will ever unless you admit yourself) you are good.