Ignore Ferd’s stupidity. JROOT is not a pirate radio station, nor was it on or off the air. Jroot is a website – Jrootradio.com. It is available on the Web, from their phone app, and through other Jewish Streaming apps such as Jstream. The broadcast does not ever mention any radio station.
Sometime in the past they were also broadcasting on a radio station, and did advertise it as such (hence the origin of their website address), but that was stopped by the FCC. (Not that I CHAS VESHOLOM mean in any way to agree with or confirm anything FERD said.)
Some anonymous person unrelated to Jrootradio.com has been receiving the free stream over the internet, just like everyone else, and then using their own personal equipment to re-broadcast it over the radio waves as a favor to the local community in flatbush (Brooklyn, NY.) No, this has nothing to do with the Rabbonim. There is no reason at all for any Rabbonim to exclude their content from being shared with Klal Yisroel.
Whether this is legal or not has no bearing on Jroot. The same person (or anyone else) could choose to broadcast any other content in a similar fashion.
As to why this is beneficial – there are still some frum people in this world who do not have smart phones and internet-connected computers in their homes, or at least in their kitchens when they are cooking for shabbos. But they do have radios. Once upon a time radios were very cheap and easy to obtain, and if they have a stereo system CD player, or Tape player, it probably has a radio too. Even simple MP3 players (Sansa clip for example) have radios. So with the broadcast they can listen to shiurim or Jewish music in their homes.
I am just trying to explain the facts, defend the Jrootradio people and distance them from any suspicion of wrongdoing. It is not my intention to take sides on the legality of the broadcast.