@tonyismad said:

I wish that wuss had tried to stab Maggie so she could REALLY have an excuse to kick his ass.

I actually thought he'd attack her, and she'd fight him off but end up with a knife wound to the stomach and lose the baby. Either Gregory would be killed by Maggie or condemned by his own people. But he was too much of a coward even to stab her in the back. As a result, Negan now knows that Rick is planning to move against him. He probably doesn't know about the Kingdom, or the junk people, because they never shared those details with Gregory, but (as they showed in the preview clip) the Saviors are headed to Alexandria in force.