If that's the Berenson quote, no that has not been proven to be true, though his language is imprecise. mRNA vaccines do greatly reduce transmission, they do stop some infection. He doesn't seem by this quote to understand vaccine efficacy. It's not accurate to think of a vaccine as a therapeutic with a limited shelf life. mRNA vaccines don't help after you have Covid which would be the definition of a therapeutic.
His tweet is inaccurate, was at the time, still is.
Now should he have been banned from twitter. No, I don't think anyone should. I don't think that's the best way to deal with misinformation. I also don't think anyone should get medical advice from social media.
Berenson did not have his twitter reinstated because this statement was found false.