IMO the Conservatives didn't focus on this because they wanted to frame Rwanda as the sole method of tackling the issue.
Spreading resources over a number of different avenues would have undermined that.
Good to read that Cooper & Bas Javid have a positive working relationship, not suggesting that should be a surprise just that it has to be influential in making systems work well.
Interesting that there is a reference in the last tweet to potentially implementing some off shore processing (so different to the Rwanda plan) - I'll want to see how that checks out financially and whether they actually have some evidence that it functions as a deterrent as I've seen diddly of that so far. They won't get a free pass on that.