My paper did show that the advantage decreased with the block reward. However, in that limit, it also seemed to imply that a network state would appear where the revenue per unit hash decreased with increasing hashrate which should be impossible as just discussed.

In a followup email, I showed how the origin of this effect stems from the orphaning factor used which doesn't preserve the full network revenue per unit block. This led me to correct my assertions by pointing out that our miner profit equations seemed to be just lower bounds to the miner's true expected profit. As such, just because the lower bound on the revenue per unit hash advantage decreases with the block reward, this doesn't necessarily imply that the real revenue per unit hash advantage does also.

I suspect that the orphaning factor used, independently of the specific form of the block relay time, is incorrect or incomplete as stated.