Hopefully, this isn't just posturing before an approval. IMO, AT&T needs competition. If it were up to me, I'd turn this around and force AT&T to sell off some of their infrastructure to T-mobile at an attractive price, in order to spur more competition.
If that sounds like it is against my general 'keep government out of the way' stance, it is, but in this case there is not enough competition to be a true free market. I think some govt action could help level the field, restore a degree of 'freeness' to the market and that would be good for consumers.