This isn’t a boycott that is organized to punish a company. It’s just a lot of normal people disgusted with an ad and therefore disgusted with a product. Something similar happened to Schliz in the 1970s. In that case, people found Shlitz’ ads offensively stupid and stopped buying the product. Schlitz permanently lost much of its market share. There was no boycott; just people reacting to a bad ad. Bad ads lose customers just as good ads attract them.
That’s the best approach, just go about quietly and boycott. The one thing this freak can’t stand more than anything is being ignored.