The basic premise here is that people with these lost episodes 'stole' them from bins after they were thrown out by the BBC, so don't want to admit this to the BBC, as they are worried that the rather large corporation that the BBC is, will take them to court and win.
Ex-BBC archives staff. They have had an amnesty in place for decades. They will let you keep the recording if you wish, they just want to make a copy. Any serious collector would know this. The article is quite dreadful, Franklin the main interviewee has criticized it apparently.
chances are if you have them on DVD or VHS they are already found, most of the missing episodes only aired once and all of them aired before home recording.
Agree, applying the standards and beliefs of today to 60-70 years ago is quite tricky though. They needed the space, media was expensive and so reused. They just did not foresee repeated content as being valuable... today.... we like repeats!