Well there's no indication that he's against paying, just that he looked for and failed to find a viable OSX alternative.

It's not listed in his requirements and Win10 may satisfy him.

There are lots of free things in life that have an inferior free alternative or only free alternatives and this may be one of them.

Well, it was you who said he should pay for Windows if Rails was his sticking point.

And I said you don't need to pay for anything if you want to do Rails programming. In fact, here, the "inferior alternative" for this task may be the proprietary one.

Another thing would be using his computer for gaming. In that case, I wouldn't object, of course.