That's a good question. I definitely recognize the dilemma it creates, but I think it also sets up a nice potential conversation along the lines of "opinionated compared to what?" Which can lead to what is meant by 'opinionated' in the first place, which, under the right circumstances, can be a really valuable conversation to have, especially if your team isn't on the same page with why you would want something like Sinatra vs Rails or anything else.

I've never found that it causes any problems, but since I have been primarily in the .NET world lately, it's pretty rare for people to be all that familiar with anything elsewhere, and if they are, they generally get what I am going for when I say it.