May I recommend a feature request. If the system is set to hold, the HAI snaplink program turns hold off, updates the temperature, then turns hold back on.
As for the feature to automatically turn hold off from Snap-Link; I think this is unlikely. For safety reasons this probably should remain a manual process. Usually when the system is on hold it is for a reason and should not be "accidentally" overridden?
There is a question mark at the end of your sentence, so I assume that leaves space for some wiggle room.
I guess it depends how people use the hold system. In my case it means, right now I want you to stop following your programming and hold the temperature at this particular point. At some points, I may want to adjust the temperature it holds it at from my iPhone.. I fully understand the reason to not allow programmatic changes when it is in a hold state. But honestly, there should be no difference (from an end user perspective, not a development perspective) if I am adjusting the temperature on my iphone vs. standing in front of the thermostat.
However, I do firmly believe the current behavior of updating the display of the temperature and then flipping back to the hold temperature is not very user friendly. At the very least a modal dialog should popup informing the user that to adjust the temperature they have to take the thermostat out of hold mode.
I liken this to having my iPhone in airplane mode. If i am in airplane mode and go to access the internet the iPhone doesn't just not let me navigate anywhere, it pops up a modal dialog letting me know that to continue I have to leave airplane mode.