I got in touch with Sophos as the response from ZOS was... non-response and they recommended that I did not run the executable until I received clarification from the publisher.
Given that I kinda need to do that to play and that I don't fancy my odds on ZOS commenting on the matter I try to run it as 'isolated' as I possibly can - sandboxed most of the time - because as we know from the TOS if there are negative outcomes from using ESO that's on us too.