Redleg, interesting speculation on your part, but nothing of that sort or like occurred or was hinted at in this case. They was no boycott in the end, but all that would have been done was pashkevalim plastered on shuls bulletin boards declaring a boycott. And some leaflets handed out to patrons on the public street before they entered the establishment, with the same printed message including a list of local rabbonim who the community respects that would have supported the boycott.
Entirely legal in every which way.