Yeah, but there's a steep difference between that and "pester us and annoy us". That's like saying that marketing should make you keep thinking about your project. If you were a marketer, would you spam people and irritate them constantly with email, or would you be tasteful and let them discover for themselves?
"Keep us thinking about your project" probably works best if you're constantly updating your project. Keep building, gently announce releases - not TO David Cohen, but just on Twitter where anybody can see what you're doing - and show that you guys aren't desperate. TechStars (or any other seed funder) is unlikely to accept the people that most want to get in. They'll be accepting the groups that put in the most effort to their project, who showed they could create without worrying about their funding.
I don't know anything about the folks that run TS, but they'd be terrible investors if they let something like overly frequent updates determine how they invest.
The simplest explanation is that they didn't like the team or the idea as well as the other options available to them.
All that's left up to the reader to decide. This is what _we_ did, and it got us rejected. We're pretty sure we followed directions both literally and in spirit. However, we didn't get selected. Maybe fewer emails would have helped, but I doubt it.
I, too, wondered if all the emails were at a level that might be considered annoying, but I guess only the people involved can say that with certainty, and apparently they didn't tell you to lay off.
BTW, ever read the book 'Growing a Business'? It's one of my favorite business books; it's about a mail-order garden tool business (which is what triggered the association).
"Make us keep thinking about your project."