Do you know one industry that likes very much tossing closed-source proprietary blobs over the wall?
Game studios, and everyone that works in the games industry providing tooling for AAA studios.
You know what else is common in the games industry? C# and NDA's.
C# means that game development is no longer a C/C++ monoculture, and if someone can make their engine or middleware usable with C# through an API shim, Native AOT, or some other integration, there are similar paths forward for using Rust, Zig, or whatever else.
NDA's means that making source available isn't as much of a concern. Quite a bit of the modern game development stack is actually source-available, especially when you're talking about game engines.
And you can still internaly have it, if your deps have sources, or compile artifacts for only allow single Rust version (additional rules may apply).
There is work on Rust ABI (crabi), but there isn't a huge push for it.
Thus it will never be even considered outside the tech bubble.