And although it's just one data point, I've personally started visiting iMore because I came to recognize their content through Flipboard, found it interesting, and wanted more.
Maybe I'd glance past 100 TPM articles on Flipboard and never read them, in which case TPM isn't out the traffic. Or maybe I'd start skimming those articles because I've started to associate their icon with interesting content and convert into a regular view. The odds of that happening are admittedly low, but the odds of that happening if their content isn't available on my news consumption platform of choice is approximately zero.
But ultimately it's TPM's call. If they want to restrict it, then I completely defend their right to do so. I just don't think it's a good business idea.