I like the practice of occasional team code reviews that include the whole team the architects, but then lots and lots and lots of code reviews between two or three members of the team.
If it's really tricky or sensitive code, then enlist the architect or senior members of the team.
Honestly, though, it sounds kind of ridiculous having an architect do code reviews. He should be doing design reviews, or occasional code reviews informally to share his expertise. The engineering team should take responsibility for the code. If there are problems, then they will get better at it with time. Sounds to me like there's something a little broken in the dynamics. Maybe someone has some control issues?