I don’t think that any rational citizen is out there arguing that capitalism itself is somehow objectively foul. That’s a strawman argument. What people are saying is that the current version of the American “capitalist” (arguably — if America was truly a free market, domestic oil companies would be a distant memory by now, not to mention most of Wall Street) system is not a well-regulated market, but a hegemonic and monopolistic nightmare that serves only those individuals at the very apex of the profit structure — and actively harms all the rest. I think this is not only a reasonable point to make, but an urgent one.
One other point: as I’ve mentioned before, the Republican ability to unify and disseminate their messaging is awe-inspiring even considering its repugnant content. The reason Hickenlooper is resisting being labelled a capitalist is because the Republican messaging platform has successfully framed the public argument in terms of “Capitalist (read: Republican) v. Socialist (read: Democrat)” — even though the actual conflict is between “Executives and Heirs of Immense Corporate Fortunes V. Everybody Else In Literally The Entire World, If We’re Including Climate Change In The Conversation”.