The comic could have cut the 4th panel and not lost the point. In fact the presence of the 4th panel is the problem here. It makes a implied sweeping generalization which is by and large what (as best I can tell) a fair number of people (likely in said generalized group) take issue with.

Nothing really difficult to comprehend as far as I can tell. Generalized negative statements about generalized groups are usually made in bad faith. Simple as that.