@holdback would obviously harm disguise in other ways.
However, the suggestion to conceal your health by holding back shouldn't be necessary.
I've been saying A LOT lately that players who guess which of the 40 possible player-run characters they know about is involved with something are often WRONG, not that that excuses the small-world metagaming but it highlights the flip side too: Players who believe that they are the victim of someone else's small-world metagaming are also wrong a lot.
The frequency with which people on both sides of this are wrong influences the seriousness with which I take any and all @ideas related to reducing metagaming potential with new code.
Hiding the "condition" is a good idea just because of the nature of disguise (you can't tell what they look like, how are you supposed to know how magnificent their condition is), not because of some perception that people are abusing it.