Normally I'm not a particularly big fan of trademarks (eg, Facebook was a term Zuck took that was already established to describe college year books, he shouldn't have been allowed to get that. It's also somewhat descriptive, which is another no-no on trademarks). Frappuccino is a pretty unique (and meaningless) word that Starbucks spent considerable monetary resources to acquire from George Howell [1] and further used its marketing budget to ensure it had meaning in the consumer mind.
I think if they don't want the word associated with Alcoholic beverages I am pretty sure they are right to ask this guy to cease and desist. Also, if they don't, and for whatever reason this guys beer becomes popular and loss of distinctiveness occurs, they may lose their trademark via abandonment.
[1] http://en.wikipedia.org/wiki/George_Howell_(entrepreneur)#St...