Yeah it's crazy, and apparently many don't like the rule, but they actually aren't allowed to talk. I am sure many do, but it would explain why Josh got a little flustered there-
https://torontosun.com/2017/04/04/a-closer-look-at-the-nfls-off-season-training-rules/wcm/69531d7c-a3c5-4a63-82b0-67d9bb1e0261