They pointed out during the presentation that the system could call once to a business and get the hours, then allow hundreds or thousands of users to see that without bothering the business again. Assuming it works, it could save a significant amount of time for some places.
>If people use it to flake a lot, I could see businesses just not responding to the assistant.
Then it sounds like incentives are aligned here. Google needs to not allow users to abuse this ability so that businesses will trust and not block them.
If they allow something like the parent commenter pointed out, they would sour relationships with businesses who would promptly seek out ways to block or decline calls from this system.