I've seen both of those articles and neither actually states that excessive N increases the occurrence of angle wings on cock-hops? I was fortunate enough to speak with the head of the USDA breeding program in Corvallis back in the early 90's and he told me it was a trait that occurred in certain varieties more than others. It's actually interesting when looking at how each statement is worded as the UVM article more accurately states that too much N can increase "unwanted VEGETATIVE growth" and the second leaves this quantifier out:
"It is important to not apply N after flowering as this can lead to unwanted vegetative growth. "
vs.
"Too much Nitrogen late in the season can give you unwanted growth and can hinder the alpha acid content of the hops"
What both of these statements are getting at is that if Nitrogen is available in excess at the point when the plants should be transitioning into the reproductive stage, they will more likely be tricked into remaining 'vegetative' which will cause them to produce more leaves than cones (less cones = less oils & acids).
There are mechanisms in plants that dictate how and when they perform different growth functions at different stages of growth (I actually can't remember half of them from back in the Agronomy days at Ohio State) that many folks think is a response to their fertilization practices. Knowing the differences in the varieties you grow does certainly help dictate how each is managed during the growing season as this article very accurately describes:
http://www.uvm.edu/extension/cropsoil/wp-content/uploads/jason-perrault-transcript.pdf
