Little quick to call it a valve job based on that little bit of testing/information, unless he seen/heard/noticed something you're not aware of.

Might have a couple busted rocker arms or just fell off, push rods bent or just fell out of place. Wouldn't be the first time for either one of those.

Could be cracked/broken rings or pistons.

Valves generally don't leak to the point of 100% compression loss and yet remain in place. loss of the keepers yea, valve sucked into the cylinder for example but you'd tend to notice that when it happen. It makes a little noise when that happens.

Valves bent or burnt to the point of total loss of seal yet remain in place you'd hear it.