Personally, I would never have agreed to this based on my understanding of the situation. It's clear from the article that Ecquire evolved from Dropcard, even if it is an entirely different product now:
"Ecquire was getting further and further conceptually (and technologically) from Dropcard"
Almost every tech company evolves dramatically, and rarely resembles its former self after four years. If one contributes substantially in the founding stages of a company, I believe one should end up with something, even if it is a reduced stake. The company would not have made it where it is without Ariel and Anton's participation in early failed ideas or admission and participation in the incubator.
It's safe to assume their contribution exceeds zero percent, which is what the Tal pushed for and Ariel and Anton agreed to. No investor would have agreed to this, why is it right for Ariel and Anton?