I don't see anything on the DTA page that talks about only certain cars using it...https://drivethearc.com/#sec-about
The funding comes from Japan. I could understand you saying the system is only for Chevys to use if GM put up the money, or Ford, etc. But they didn't.
I think it's okay for Teslas to use as long as they practice good EV etiquette and don't stay connected too long when other cars are waiting, etc.
And, by the way, the free charging aspect of the project is for a limited time and then it reverts to eVgo's pay for use billing system...