There’s any even more compelling reason which has been posited on one of the other threads here, which is that it was essential to cover that section of the certificate to hide the fact that there was NO number. They could not put in a fake number because it could then be checked for accuracy.
“They could not put in a fake number because it could then be checked for accuracy.”
You are quite correct, but I’ve decided it is also in accord with human nature for a staff member to cover the number on a legitimate certificate of a well known person, “just to be safe”. What the actual case is here is still uncertain.
The certificate number is 151 1961 NNNNNN.
151, YYYY, NNNNNN where NNNNNN is the birth count at that point in the year. It’s not top secret.