Tottigol, PHI's EMS WX limitations are more restrictive than Part 91 and are followed on all legs, wether Part 91 or Part 135. So in this instance, that would not have made a difference. I agree with you though that from a regulatory point of view it would be much better to declare all EMS flights Part 135, regardless of wether there is a patient on board or not.
I know this will never happen but I sometimes wonder how much safer it would be if every EMS helicopter had a designated, protected service area and if dispatch was a government operated, nationwide entity. No more trying to muscle in to each other's service areas; no more helicopter shopping by 911 operators. EMS operators could simply bid on service areas and be assured of a certain amount of business, handed out by an independent dispatching agency.