Any knowledge why Windsor Castle is not open for tours May 30-June 4?
I'm not seeing that the castle is closed on any of those dates under "Opening times" on the official website:
https://www.rct.uk/visit/windsor-castle
Where are you seeing that info? The calendar shows tickets available on June 1, 2, 3 and 4, although St George's Chapel is closed on the 4th (Sunday). That's a normal closing, and not a day I'd choose as the chapel is one of the most interesting parts of the castle.
May 30th is a Tuesday; the castle is closed on Tuesdays and Wednesdays.
My mistake. I didn't realize the Castle was closed on Tuesday and Wednesday. Sorry!