“calling McCain a liar?”
Nope. There is no KGB, it is different agency, name, and initials. I think Senator McCain was referring to Putin’s work history inside the KGB, not implying the agency actually exists now.
‘Gramps’ was not meant to give offense. Just pointing out that worrying about KGB, USSR, et. al. is a little old-fashioned.
McCain's remark was about the man Putin and his relationship to the former KGB. Putin is still here.
It was an appropriate comment.