I can't see how increased selection pressure could ever lead to stasis (equilibrium). To me this is an example of a supposed effect without a cause. As the saying goes,"sho' me the money."
Let me give you a hypothetical situation to try and explain this.
We have a population of common brown skroats. Common brown skroats spend most of their time hanging out on tree trunks. There is a fairly common mutation among skroats that will turn the offspring of a brown skroat day-glo orange. The general population, being brown, is rather hard to see when sitting on the brown bark of a tree, but one of the mutated day-glo orange skroats can be seen from quite a distance. As such, the day-glo orange mutants are seen and devoured very quickly, leaving behind their brown siblings to reproduce and make more brown skroats. So long as the color of the bark of the tree does not change, the selective pressure will act to keep skroats the brown color that most of them are.
Selective pressure reinforcing stasis, or zero change. If the selective pressure of brown skroats having a survival advantage gets stronger, it will only reinforce the stasis that much more.