The surgeon is unaware of the specific valve type an individual has. The decision should be made by the surgeon (i.e. what INR do they want) and your cardiologist (how low can the INR go and for how long before your valve needs bridging).The gall bladder surgery - cholecystectomy - is minimally invasive. The tools go into your body through small incisions in your abdomen (unless they've figured out some way to go through your mouth).
There shouldn't be much blood lost. Maybe the doctors are concerned with potential blood loss if the robotic surgery encounters a problem and they have to open you up.
This is the reason that they want your INR to be down.
While it's possible that clots may develop post-op, they'll probably have you on heparin while you're in the hospital - but may discharge you on the same day as your surgery.
If you take your normal dose for three or four days, your INR will return to normal.
OTOH - bridging WILL help prevent clots from forming while your INR gets back to normal.
In the case of this surgery, it may make sense to bridge for a few days after surgery.
But, of course, the decision should be made by your surgeon - she's done a lot more of these operations than you or I have....