From what I've read, these tubes were commonly used for low power VHF FM broadcast stations in Europe. That's probably where the shielded socket was used. It looks like they went to considerable effort to make such a socket. I assume it was necessary to do so.
Using it at HF would require a physically larger tank circuit and with the single-ended tube design it can complicate the layout of components. I'd still keep good I/O isolation in mind. But, maybe I worry too much.