Have you heard the expression "Freedom isn't free"? People aren't saying "Liberty isn't liberty", they're saying "Liberty isn't free of charge." Similarly, this person is saying "Libre software isn't free of charge." You're not informing them of something they didn't know.

Any idea why not to use 'freedom' term instead of 'free' and explaining it again and again. Freedom Software Foundation Freedom software etc ... What prevents renaming?

The word 'freedom' is itself highly politically charged in a certain very influential country. It has various context-dependent nuances best left undisturbed outside of targeted party-political discourse.

When we talk about free software, we're already explicitly invoking "free as in freedom" though. If you want to avoid the " freedom" rhetoric then you should talk about open-source instead.

I prefer "freedom-respecting software" myself. It parses better.

Just speaking for myself, the bad grammar of "freedom software" kills it right away for me :-)