Well, people don't go to Costco for commentary, they go there to buy things. So a more apt comparison would be a section that sells things that certain groups may find offensive - e.g., sex toys, confederate flags, bibles, guns[1]. The metaphor holds mostly, Costco is free to do what it wants to cater to those people, but I don't think it's unreasonable for some groups to want to fight to hold on. It's hard to make blanket statements about some of the groups - of course, that's less true for some than others. I don't have any horses in this race, personally, I don't think anyone is planning on banning r/corgis or r/noideadogs.
As for profitability, I'd argue that stupid people with strong opinions and a need to vocalize them are advertisers favorite kind of people. They're probably surprisingly profitable.
[1] Don't assume I'm putting any of those on the same level as each other, just making a list of what I suspect are violatile items to some groups.