I think that's probably a mischaracterization. First of all, the hand is not held in a fixed rigid shape. Yes, the arch of the fingers of the claw is stable, but the spacing between the fingers must adjust as you play up and down the neck. When your hand is properly calibrated, this adjustment happens automatically while you are playing...so your intonation is good and few corrections are required.
When I can hear my instrument clearly, I can adjust on the fly. But, in large symphonic ensembles I generally find it impossible to hear well enough to adjust. In this situation, I rely more heavily on hand calibration. This calibration is achieved through practice.
Here's an example:
I used to switch between fretted bass guitar, upright bass with a pickup, and an electric upright. Switching to bass guitar did not impact my intonation, but switching back and fourth between UB and EUB could be problematic in some settings.
In big band I was part of the rhythm section and played loud enough that I could adjust intonation on the fly. So I could easily switch back and fourth between all three instruments. In concert band I primarily functioned as part of a larger bass section. So I played at a volume level that allowed me to blend properly. I frequently could not hear well enough to adjust on the fly. So I had to rely more heavily on hand calibration.
There was some material we performed in concert band that I would have preferred to play on EUB. When I first got the instrument, I took it on tour. But what I found was playing the EUB significantly degraded my intonation for section work on the UB. My priority in concert band was the section work, so a week or so before tour prep began I put the EUB away and pulled out Simandl to work on calibrating my hand to the UB.