SSPX priests are not validly ordained. That’s the whole point of bringing them back in the episcopal fold so that they can be validly ordained. It’s no different than if you or I were to declare ourselves a priest.
Actually SSPX priests are validly ordained. The Church is absolutely clear on that point. That’s why SSPX priests can easily be incardinated into other orders or diocese if they so choose. They do not have to be (re)ordained. I have known two such priests.