He can know about it as a concept without really understanding it and if he he treats the dev team as a code producing machine then he could be ignorant of how much technical debt there is. Or maybe there’s an asshat on the dev team telling him there’s no technical debt.
The boss probably isn’t lying about no technical debt. He’s probably just too dumb or ignorant to know about it.
If he mentions it, one has to assume that he knows enough about it to lie.
He can know about it as a concept without really understanding it and if he he treats the dev team as a code producing machine then he could be ignorant of how much technical debt there is. Or maybe there’s an asshat on the dev team telling him there’s no technical debt.