Being bothered by something like this isn't going to help you - at best it'll make you seem petty and rather vain.

"advertise an online masters as a regular one" --> This makes no sense to me.

A friend of mine just got their masters of computer science from the online program at Georgia Tech and the diploma does not make a distinction between conventional on-site vs off-site.

If NYU is anything like Georgia Tech, the diploma is identical regardless of whether the student took the courses online.

Therefore, there is no "advertisement" that takes place. It is a regular master's diploma conferred by the academic institution. If you have problem with it, take it up with the registrar's office.