Well, that might be true. But if you base your whole project around somebodies service, and they change the ToS, or shut it down, what right do you have to complain? On the other hand, if you use GMaps only on the contact page - no big harm done. It's all about trade-offs.

The conservatives might want to contribute a little to a FOSS alternative, that might be of lower quality - and benefit all as a result. And cover all their bases as well.