5G is coming in two phases. The first phase rollout uses existing 4G towers for signalling and new 5G infrastructure for data only. 5G microwave is point to point, and crap at getting 'in the valleys' as they say. Until there's enough P2P infra on our streets, 4G towers will continue to be used. The plan is to have full 5G by about 2024 - assuming current rollout plans with Huawei H/W. Using H/W by other manufacturers will set things back by 18-24 months.
Seems to me like POTUS is buying time by stopping the rollout as much as possible, until it can be canned completely.