It would seem Trump had been "courting" Ayers for some months now, perhaps half a year, while sidelining Kelly. No doubt promises of great things if/when he came on board...all the usual Trumpian BS to get what/who he wants. So when it came to the crunch and Kelly has resigned/been fired, Trump naturally expected that Ayers had been buttered up enough and was "on board" (felt the embrace? Is that the term?) to walk into the position. But Ayers wasn't buying, probably because he is halfway smart (well, he works for Pence). He has seen close-up what happens to others in Trump's orbit, can read the goat-entrails clear enough to see a spectacular flaming crash for the Trump team, and so can see the writing on the wall for his career if he joined them now. So he has done the only thing he could - said "No" with out saying "**** No!!".
It has been a classic and spectacular misunderstanding on Trump's part, but almost entirely predictable. Thing is, now Pence has had a really big fillip by having his own team remain loyal in the face of his predatory boss's poaching raid.