score:7
A non-visa national, such as Argentine nationals, can pass in and out of the zone as long as the 90/180 rule is observed AND the person satisfies the landing interview with a valid premise. As a general rule, all interaction with border officials is governed by personal impact and articulation skills (along with demonstrating an understanding of the rules), so be prepared for it.
In your case, you can present an itinerary of the talks you are giving along with any personal tourist side-trips you have planned.