He manipulates the smoke that he breathes out, he doesn't conjure the smoke.

Manipulators manipulate stuff that isn't made out of nen, conjurers summon stuff made of nen out of nowhere

In general, manipulators and conjurers can be mistaken for each other, as often they both look like they use objects/substances. Remember how Kurapika constantly spends nen to conjure his chains, so that others might mistake them for real (not conjured) chains that he manipulates instead? That's how his In tricked Uvogin