Timing is everything !!!.
He's likely waiting for the Toronto job to open up, and wants to make sure he will be available, and well relaxed to prepare for it.
Trotz has won 8 playoff rounds in the last 3 season including a pair of final 4 appearances, after coming off a Cup in Washington, while Keefe has won a measly 8 games total, which is mathematically just the minimum to win 2 playoff rounds combined, if you could steal playoff wins from previous years to make that fact happen.
The end is near, the writing already on the wall, and besides if he really wants to get paid well, then certainly Toronto is his best option for that.
However Leafs after all are paying Babcock $5.875 mil per season of his $50 million contract, until his eight-year contract expires on June 30, 2023. Dubas forced MLSE to eat that cost, just for the opportunity for him to have his boy Keefe coach the team to round #1 losses annually, while they double down on coaching costs for the organization. Babcock was already the highest paid coach at that time, so that cost gets factored in by adding in Keefe salary now, and then a new coach, would be paying 3 coaches on the books at the same time .. Since Trotz won't come cheap, they're basically pot committed to Keefe like it or not.
The Shan-a-plan never included paying 3 head coaches all at the same time, just to try and win a single playoff round, heading into his 9th year in charge of hockey operations.. Pretty soon someone in Ownership is going to start noticing the problem might be much higher up then just coaching, when that kind of financial investment starts showing up in the MLSE financial records.
So the timing in Toronto is all wrong at present. It will be good timing next summer, for when Leafs clear the books of all their financial obligations to former coaches, to bring in a winning coach like Trotz. IMO