Charlie,
An email and letter campaign will not get them any free advertising. However, it will show the Met that you think this is wholly inappropriate.
On the other hand, a raucous rally, with a loudmouthed publicity hound, shamefully wearing a tallit, hamming it up for the media will generate free publicity for the Opera and negative press for Jews.
BTW, the following was reported today, that Avi Weiss, clad in his ubiquitous shawl, was protesting outside the Met.
Hmmmmm.