I mean, real talk: every time I ever objected to something like that, they always said something like: "oh, we don't care what you do in your off time. You can

I mean, real talk: every time I ever objected to something like that, they always said something like: "oh, we don't care what you do in your off time. You can always e.g. ask for an exemption for specific open source work later", and "its very unusual for us to change this, we've never had anyone ask for this kind of thing in the past". If I had followed this advice, I would have missed out on one of the best jobs I ever had. So, just YMMV.