Ludwig Boltzmann was a very important scientist (or perhaps I should say that his scientific contributions were significant). However, if I recall correctly, his peers didn't agree with his theories and, I would assume, they wouldn't have called his theories scientific -seeing how they basically assumed atoms in a time when that was controversial.

So, I too consider that agreement from others isn't a prerequisite for being a scientist. I also agree that "making and testing falsifiable hypotheses" definitely qualifies as doing science.

However, perhaps that's not the only way to do science. In general, there is that whole set of criticisms on the limits of falsifiability (with Kuhn et al). In particular, I'm thinking of cases where arguably the technology isn't sufficiently advanced to perform the measurements necessary to directly test the hypotheses (e.g., how quantum physics progressed). Arguably those doing all the thought experiments, modeling, thinking through consequences of those hypotheses and comparing with what they could measure were doing science -though those weren't falsifiable hypotheses at the time.

So what I'm saying is that your requisite is sufficient but perhaps isn't necessary either.