To be fair. Every operating system assumes these things. At least the seL4 team has made this explicit. Secondly, there is a tiny amount of this code amounting to a few hundred lines of assembly and there are numerous verified hardware projects underway. Furthermore, as time has gone by, many of the original assumptions have been whittled away. This is by far the most robust operating system ever written.

Sure, I agree. There is indeed some work being done in making some of those parts more trustworthy. That being said, it will probably be sometime before that technology is usable by the average person. I'm really interested in seeing what they release.