that actually makes a bit of sense. a lot of legends are just flowery ways of telling real-life acts.
as for those quotes from the 1400-1500’s literature, they are most likely wannabes trying to steal some glory. The Arthur legend dates back to pre-1000 AD I think. every castle in Britain has been claimed as Camelot over the last 1000 years.
Wikipedia says late 400's AD to early 500's AD. Not many records survived from that time. And you are right, just about every Castle, Tower and Manor Home in England and Scotland has made Arthurian claims. As has one of my surname ancestors old lost holdings in Scotland. Do not take much stock in those claims though. There is even stuff that predates Arthurian claims that is just as interesting. Old Pictish holdings and lots a strange stoneworks. Back during the last major Ice Age, the Island was connected to the European mainland and represented the ancient European coastline.