He surmises that some people think that Google and Yahoo should be more insulated than others because advertisers (should) know their ROI from their spend at Google and Yahoo.
I think Google and Yahoo are both vulnerable - Yahoo more so because of the brand advertising stable of customers that drives its profits. However, as I've posted on in the past, I think the decline of the mortgage lead market will hurt them both when things slow down.
In other words, I agree with Blodget and I don't think Google or Yahoo are very insulated from the usual advertising cycle. When it comes, it will hurt.