Google is supposed to be
the data driven organization that changes things in a way that will minimize collateral damage. Even if Google Shopping doesn't draw much traffic in relative terms, at Google scale I'm sure it provides meaningful revenue to all sorts of companies that have products that include the term "gun" that do not include weapons. To make such a change and not methodically try to reduce the blast radius for these people effectively proves that whoever is in charge over there is not rolling out changes to search algorithms in the way Google is supposed to be famous for.
I worked on search algorithms for an ecommerce site that would kill for the kinds of traffic Google Shopping probably gets, and the idea that this would ever pass code review is laughable because of all of the blatantly obvious negative effects it would have on recall. At the very least, you would whitelist bigrams in query logs that go along with "gun" that do not include weapons. This is a truly amateur move, several steps away from what I would consider acceptable from the worlds premier search organization. I would fail a student taking an information retrieval course on a question if they provided this as a solution to removing a category of products from a search engine.