If I were a Rust user, I'd be really afraid of what will happen to Rust when Microsoft gets hold of it in any way. Just look at what happened to C++ after it got popular because of Windows/Visual C++ and the strong ties between Microsoft and WG21 in the 90s/00s.
Microsoft doesn't "get a hold of" Rust by using Rust, any more than you get a hold of it by writing Rust programs.
With C++ they had their own compiler implementation, which obviously diverged. This is common for independent code bases. Whereas with Rust they're contributing positively to the main compiler implementation. Just one example - see all of Ryan Levick's (@rylev) contributions to Rust. Not just with code, or with tutorials, but in regular unglamorous work like running weekly compiler performance meetings.
Microsoft is also a platinum sponsor to the Rust foundation. The foundation uses this money to directly sponsor folks working on the language and library authors.
To quote Steve Jobs: "They just have no taste."