Humility will likely become one of his greatest strengths, even in interview settings. Yeah you ought to ham it up a bit with the non-technical recruiters, but once you're in a room (or more likely zoom call) with real developer talent they tend to smell BS fast.
Humility, at least in part, comes from having a vision for all of the things you could do better. If he reframes his achievements from "its not good enough but it doesn't do x,y, and z" to "here's what I've done, and I'd want to do x,y, and z next" he's going to kill it