We've been down this road before.
The UK would look pretty silly if they banned Huawei equipment and then had to turn around and reverse themselves on that when the US decides that Huawei are no long a "threat to national security" because the US had finally signed a good enough trade deal with China (currently under negotiation).
The US declared that Canadian steel and aluminum were "threats to US national security" as well, and slapped massive tariffs on them until Canada said we weren't going to sign a new NAFTA deal with the US until they were retracted. Then all of a sudden Canadian steel and aluminum were no longer threats to US national security after all and the tariffs vanished.
The US has been making systematic use of "national security" as a trade negotiation tactic because they see it as a loop hole in WTO trade rules, despite their mis-use of it being so obviously transparent. They want to rope other countries in to supporting their blockade on Chinese 5G kit because the global market is so big that the US being the odd man out wouldn't really phase Huawei much.
This is the way Trump rolls. We've been dealing with this sort of thing living next to the US on a regular basis for a few years now. He's openly admitted to simply making up "facts" on the spur of the moment when dealing with the Canadian government in order to derail the conversation when negotiations weren't going his way.
Canada are also holding off on making any decision on this, partially in order to see what the UK will do. In Canada all cell phone network kit must be reviewed for security problems, not just that from Huawei or China. Canada's equivalent to GCHQ have found no serious problems with the stuff from Huawei when used in the manner which the telecoms carriers are proposing. Any problems with Huawei kit are purely diplomatic and politically related, not security or technical ones.