Arbor (disclosure: my employer from 2001-2005) is the commanding market leader in DDOS data. You'd assume any service built in any way on DDOS data would have some kind of relationship to them; they've instrumented pretty much the whole Internet backbone.
I know, I've used Arbor in the past and my current employer does as well. I've had nothing but good experiences with them... Just from the about page, we get two Google Research related groups + Arbor which would suggest a relationship with Project Shield
And Arbor Net is one of the 'trusted' partners