They aren’t going to sue AT&T over a non-legally binding statement in a speech nor would they have legal standing to do so even if they wanted.
It brings up an interesting point. The supposed motivation of the tax cuts was under the guise that it would increase jobs and mean more money for employees. I have a hard time believing anyone who voted for the tax cut actually believed that. And the people lobbying for the tax cuts are not legally obligated to make good on any of the things they said would happen when the tax cuts went through.
The most likely thing is the people who were elected and passed the tax cuts are held accountable and then the cuts are rolled back but don't hold your breath.