Unfortunately, as another Pakistani, I can tell you first-hand this account sounds very credible. I've known startup founders coming back from conferences in South Asia being interviewed by "Intelligence" and their companies audited just because someone was curious.

I've personally been tried to be interviewed for having a meeting at a foreign Consulate. The "Intelligence" may be hostile to journalists but their conduct is toxic to all civilians.

Talking about this encounter is the best thing he could've done. Think of it as protection against enforced disappearance. He's already on a "watch list", why else did they interview him?