Here’s the thing that people don’t get about the wineseller: the whole thing was staged to push Khal Drogo into accelerating his plans for invasion, and carefully scripted by Varys and Illyrio. 

Varys gets the order, but rather than hire a professional like one of the Sorrowful Men or something, he hires a complete patsy who even a relative naif like Dany sees through in an instant. And then he sends a letter to Illyrio telling him exactly what’s going to happen, and Illyrio sends a letter to Jorah, and lo and behold Jorah’s on the scene to “save” Dany and gain her trust so that he can help Varys and Illyrio “steer” Dany from long range. 

In other words…it’s not a “real” assassination attempt, it’s more of an elaborately plotted piece of theater meant to convey the impression of an assassination attempt.

A mummer’s farce, one might say…