Mateschitz and Horner completely brought this situation on themselves with their stupid antics of publicly shaming Renault. Fair enough, the engine wasn't up to the level needed but to spout that vitriol isn't going to make any other engine supplier want to work with them.
They made their bed.
I disagree, but unfortunately we are lacking information about who had discussions with who, and the timing of things, to be able to confirm what actually happened.
I'm still of the opinion that the Red Bull board would not have approved the early termination of the Renault contract without firm knowledge of having an alternative in place.