Unfortunately people who have rooted phones, who use nonstandard browsers are not more than 1% of users. It’s important that they exist, but the web is a massive platform. We can not let a tyranny of 1% of users steer the ship. The vast majority of users would benefit from this, if it really works.
However i could see that this tool would be abused by certain websites and prevent users from logging in if on a non standard browser, especially banks. Unfortunate but overall beneficial to the masses.
Edit: Apparently 5% of the time it intentionally omits the result so it can’t be used to block clients. Very reasonable solution.
But the power is too significant. If it were some small subset of positive assertions I'd be ok with this, but the ability to perform arbitrary attestation is beyond what is required and is far too abusable.