But it does matter, it practice it matters more then what is legal if we are honest.
> It isn't the FSF's job to write Rust tooling
Yes, but it doesn't mean that it's not a bad license for the given use-case.
If it's impractical, then in practice there is not much difference to the license simply forbidding the usage (iff the company cares about what is legal).
Through the question is is it a bad license for the given use-case? I.e. does Sequoia provide a rust API or do they provide a C-API written in rust.
Licensing a rust "for-rust" library as LGPL is in practice so close to GPL, that you just could have made it GPL. But a rust C-ABI library/program (e.g. a system library) is a different matter and binding in a LGPL C-ABI library into a rust project still somewhat practical doable (but still quite annoying).