So why did he not adMIT to knowing Clinton? Kinda public knowledge
Once the first admission is made, the prosecuting attorney has been given permission to proceed with a particular line of questioning, so the first claim of the protection under the Fifth Amendment may seem to cover some pretty innocuous questions, but once initiated, can lead to some pretty damning admissions.
The only questions that are NOT subject to the Fifth Amendment are name, rank, date of birth and serial number.