I have no idea who was the reviewer (academic or industry or whatever). However, he didn't actually object to the assertion that latency increases with congestion; he only raised the question of the which latency values would be typical/reasonable for a congestion DoS attack. Notice also that the relevant parameter is end-to-end latency (or RTT), not the per-device latency. And surely, there can be wide variety here (that's why we do experiments under different values and plot graphs....). The question is, what is the most important range to focus on (when measuring and comparing different protocols).
Anyway, thanks for the comments; if anyone has such data they can share, that'll be great and appreciated.