If they had invited you to a forum and you spent a few days testing your theory which would benefit them by helping secure their network , they would owe you something for your efforts.
And I would call them welchers too.
With the evidence we have so far, CfB's 30GH/s attack on bitcoin is just as possible as cynicSOB's is on Nxt.
Do you see the problem?
I like what cynicSOB is doing and hope he finds something, and I'm glad to donate some Nxt if he found a flaw,
but you shouldn't trust just words from strangers on the internet.