I don't think it is, at least in the US. What most people forget about HIPAA is that the P stands for "Portability". The entire point behind it was that someone should be able to take their records from one hospital, doctor's office, or imaging clinic and then bring it to another one without having to go through another scan. DICOM was the industry's response to those portability requirements that our government put into place.

I suppose it could be false advertising to say you support a standard but only in a way that's meaningful to your software? As a 3rd party developer, it's hard to demand another company build something into their API, based on standards or otherwise. The best you can do is throw around your market share and lean on your mutual unhappy customers to make it happen.