Whilst objectionable, I don't think Giuliani is stupid - it won't have been an accidental reveal, and I'm sure he appreciates exactly the likely consequences of the admission.
Presumably there's been some calculation that admitting to it now is less painful (or stops off an avenue of attack for Mueller) than allowing it to carry on or being forced to open up about it later.
Whilst objectionable, I don't think Giuliani is stupid - it won't have been an accidental reveal, and I'm sure he appreciates exactly the likely consequences of the admission.
Presumably there's been some calculation that admitting to it now is less painful (or stops off an avenue of attack for Mueller) than allowing it to carry on or being forced to open up about it later.