Agreed. Even so, the value of the Trademark should bear some weight in the argument - here they took a name that was already widely used by others for a use relating to beer and want to close the door behind them for future use by others where little to no confusion in the marketplace is occurring. Sometimes the law has to catch up to the facts in order to properly apply.
However, if their business were to grow then confusion would become a much bigger issue. And they've got an online store, so no doubt they do intent to grow. It's better to handle any potential problems earlier rather than later. I'm coming around to thinking that the HBS is right to ask the brewery to change their name.
I've still got a bad taste in my mouth over the way they've apparently charged into the situation guns a-blazing. They were right to seek legal advice before starting the conversation, but I think it would have been more classy to start by personally contacting the brewery's owners with a message that had been vetted by their lawyer rather than sent by him. When you choose to have the conversation start with an attorney's letterhead, you inevitably come across looking like a bully. Perhaps it worked out that way because of the lawyer's advice, though.