This is not theoretical: e.g. Debian's 32-bit x86 baseline is i686-without-SSE2 but this will include the problematic instructions so to fix this would require the baseline for the whole operating system to change or else to special-case rust to target i586.
Arguably this because Debian is not enabling SSE2 on i686 but that is just to allow more hardware to work.
https://lists.debian.org/msgid-search/d8b5003f-8543-47b3-84a5-ade34c831655@app.fastmail.com