That's because the propositions are arbitrary.

The definition of what is "Free Software" is arbitrary, because anyone could use a completely different definition and wouldn't be less right or wrong.

The proposition that "Free Software" is moral is also arbitrary, for there's no rationale. There's just some agreement because of the bandwagon effect and multiple meanings of words like "freedom", "sharing" and so on.

The simple truth is: It's sometimes useful and so is "non-free" software.