I would also go out on a limb here.
Was he mixed fleet flying?
Did he fly the 207/210 also?
How many hours did he have in the can?
Was he taught to check manifold pressure? Or just firewall it and do the old "airspeed live, rpm stable, ts and ps green?
If he was mixed fleet flying and had flown a naturally aspirated aircraft prior that would probably make around 26 inches or so on takeoff (certainly kess than 29") was he seeing what he expected to see?
Did he realize there was an issue prior to rotation?
I doubt he would have committed to the takeoff if he had of realized what was happening.
The only reason I became conscious of manifold pressure in piston powered light aircraft was when I started flying PA31s. I wasn't neccesarily checking how much it was making but more that it wasn't over boosting. From memory it was around 46". I was more interested in the single piston powered days of RPM and how the aeroplane "felt".
At 200 hours I didn't really know what is was supposed to feel like, so alarm bells might not have been ringing and I may have been in the exact position this poor soul found himself in.
This is called experience. Hopefully the folks reading this, gain some from this example.