I suspect much of the "radio silence" is a combination of "don't tip our hand" and "not reacting prematurely to Trump's bluster, but rather waiting to see what he actually does".
Plus, there is a lot that is happening.
Trudeau is in Europe discussing the situation with various leaders there.
The premiers were in Washington talking to anyone and everyone they could.
And there have been a number of contingency plans made, we just have to see which (if any) of Trump's "concepts of a plan" actually happens.
Meanwhile it looks like there is starting to be some infighting among Republicans. No need to interrupt them while that's happening.