I’m hesitant to call it a professional opinion, since I’m not confident I know all the relevant details, so let’s just say in my regular-ass opinion, JJS should have stuck to the company line, denied all knowledge, and told him to take a flying fuck at a rolling doughnut.
Your assessment of negotiating being on or off the record is also a good idea, but assuming JJS either has some expertise in or has been coached in basic source protection, he keeps his mouth shut no matter how off the record it appears to be - Clark Kent might be an upstanding, moral, and honorable individual, but when it comes to protecting sources, you don’t trust anyone that you don’t absolutely have to, no matter how upstanding they are. It’s not like there’s a rule that says you gotta give yourself up if someone asks - for all JJS knows, Mr Kent has been ringing around every office on the hill hoping to catch people off guard. You don’t know what he’s got on you, or doesn’t, so you don’t say shit.
If you are an anonymous source, you keep your fucking mouth shut. You don’t tell anyone you don’t absolutely have to, you don’t tell your parents, your friends, your workmates, your priest, your favorite sex worker, your bartender, nobody. If you’re telling anyone, what’s the goddamned point of being anonymous?