If she pushed him too hard, there was no telling what he might do.
He could snap and act out of desperation, resorting to something drastic. He might try to kidnap her, attack her mates, or even forcefully mate with her… and that would harm not just her, but her mates too, physically, emotionally, and even spiritually.
Right now, Addison could weaponize Leon's regret, turn it into leverage, and bend him to her will. The false mate bond, though originally intended to force her hand, could now serve her purpose instead. It might not be a bond of love, but it was still a connection, one she could manipulate.
In hindsight, Leon had just cornered himself into a far more disadvantageous position.