This is a weak argument because YouTube isn't a public street it's a private business
You aren't forced to use it, it is a choice
And this application (FreeTube) is for the sole purpose of circumventing their (YouTube) monetization for the sake of convenience
I don't have a dog in the fight and I'm certainly not a fan of YouTube or Google, but you can't argue it's somehow ok just because you dislike ads or lack of privacy on a "free" video streaming website
And YouTube as a private business can refuse to serve people using ad blockers or alternative clients. But that doesn't make it illegal to use an ad blocker as the parent post was implying.
If your business is taking pictures of people on the street and I decide to wear a baseball cap and sunglasses, you're just out of luck.