Except when a tenant is kicked out of their apartment with no notice, they might literally die. When Routebuilder gets shut down (with at least 2 weeks notice if not more, according to the article), someone organizing a marathon might... have to use a different, also free service?
And let's not forget that Google is a private enterprise offering an absolutely insane amount of data and access for free. The bar for "legitimate reason" to revoke API access is (and should be) legally no higher than "Google wants to." They actually go quite a bit above and beyond by having Terms that you can read and that as far as I can tell they abide by.