They do address it in the post:
> For 11th Gen systems, we also have a firmware update in progress to bring in the security updates and power consumption improvements, but not retroactively certify Thunderbolt (there are some test cases we don’t believe we can resolve on that generation, unfortunately).
Sounds like a hardware thing, which again you can upgrade
No matter what new camera I buy, the manufacturer going to ship something newer and better soon. So it is with most things in the modern era.
The blog post made it clear they're shipping all the Thunderbolt firmware improvements to the 11th gen as well, it's just minor hardware differences that are blocking a few test cases and official certification. It sounds like you can enable Thunderbolt relatively easily if you're okay with that caveat.