Interesting chapter of space history I never knew about, thanks.
Thank goodness it didn't happen- seems to me!
Anyway - says here - that the final thing that stopped it was the US, Soviet Union and United Kingdom signed the Outer Space Treaty in 1967.
That prohibits anything like this - and is why we don't need to worry about the US, Russia, China, ESA, Japan, India, or anyone else setting up military bases on the Moon :). Is in everyone's interest to keep to this treaty.