Yeah, poor little UK, it's only the 5th biggest economy in the world after all, not like the 1st or 2nd!
However, I don't see how companies alone have the power to openly strongarm governments. It would be a pretty foolish move. But withdrawing from a country's market to cut losses can be a correct move.
They wouldn't able to say "Well, you're breaking the law but because you're threating to leave, we will let you get away with it."
Giphy isn't big enough for that, but if for example the CMA requested that of Instagram, then it could be a good business decision to just leave the UK.
Also I do not think the general public will scream at their MP's to fix this problem. Not many people say anything to their MP at all about anything, and hating FB is quite popular.
That wouldn’t do anything, legally speaking. The acquisition was under British jurisdiction when it happened. This is the U.K., not El Salvador. Its system is heavily integrated with America’s. If Facebook blew off the CMA, it could find relief in U.S. courts. Given how unpopular Facebook is, State would be unlikely to intervene on its behalf.
there would be wall to wall coverage about facebook deciding the law doesn't apply to them
Facebook certainly has bank accounts in the UK. Its has offices and people working there. The UK could just take from that money.