My guess is that she's arse-covering. She wants to be seen 'doing something' and so that if there's an incident she can then point and say "I told them but they didn't listen"

It's hard to know what's actually going on behind closed doors, but it sounds like the tech companies want to do something about it and are quite prepared to work with the government on a solution.

Of course, what that solution turns out to be is a separate issue. I trust Google et al to know what they're talking about wrt encryption far more than the UK government though, so actively working with tech companies is a huge step up from the previous position (though obviously a long way still to go).

My guess is threatening, since they'd be in violation of UK law. Each of those companies have a significant presence in the UK, which I doubt they'd want to abandon over this.