This seems like a step forward. Exploding offers are generally unpleasant, usually a power play from the side that has less to lose.

It's also common practice for companies to extend exploding offers to new hires. Replace "accelerators" with "companies" and "founders" with "hires" and you get a very similar argument for not forcing people to take a job until they've completed their own decisionmaking process (this ultimately benefits the company as well, in my opinion).