So much nonsense!
When a clean wing is stalled, it does so at an unique angle. Extend flap and the whole lift curve slope (Cl v. AoA) changes. The angle of attack at which the wing with flap extended stalls will also change.
Don't worry about the re-energised airflow or any other pseudo aerodynamic terms; think of the Cl v. AoA curve as the wing's 'fingerprint' - and that it has a different one with flap extended!
For most a/c, the stall occurs at a lower AoA and higher Cl value with flap extended than when clean.