No spray buff, thats one of the few things I think they do right.NICE JOB! As for the unstripability , I put money on they used a spray buff repeatedly with a hardener.
Talking with some of their cleaners they were convinced that the floors up there just looked bad and there was no way to get them better. They decided this because someone did a very poor job stripping the floor one time and waxed over a bunch of grey dirty wax. Then when they tried to deep scrub it and saw that the grey wasn't coming out they decided that the tile is just shot and there is nothing they can do about it. So every couple of months they've scrubbed it with simple green and a blue pad, mopped it off (they don't have any wet vacs) and slapped down 3 - 5 more coats of wax.
I'm tempted after all of this to offer him a once to twice a month maintenance schedule with a topcoat every 6 months (if properly maintained I should be able to go 2 years between strip and wax on these floors). If his guy just mops it daily with neutral cleaner, not simple green, then it would stay looking that nice for a good long time. I just hate knowing that after all that work its not going to be maintained properly.