the name says it all pretty much. if the protoss player plans on a 4gate, but turtles his ramp with buildings and zealots, how am I to counter that? the proper counter to a 4gate last I knew was build AFAP and pray. roaches are encouraged but its more luck than anything else as far as I remember. granted its been a loooooooong time since I played (more than a year)
I think this would be very rare from a Protoss because basically there's no benefit to delaying a 4-gate attack.
Let's think of this from the Protoss side. The point of a one-base 4-gate timing attack is to get the maximum production at the earliest time -- a time when Zerg typically has barely any units. One base cannot sustain 4 gateways worth of production. So Protoss has a small window where this timing attack is most effective, before Zerg has had the time to prepare for it with queens, creep spread, 2-base economy, spine crawlers, and attacking units.
If the attack is delayed, Protoss gives Zerg time to build all these things, nullifying the entire point of the attack. Zerg should be on two bases already by the time the attack was supposed to happen, so if the attack is delayed, Protoss is vastly behind in economy.
If you are vastly behind in economy, the ONLY way to win is to attack immediately and try to kill your opponent. Turtling only puts you further behind, as your opponent (Zerg) expands his empire.
So as Zerg, the simple advantage you have in this scenario is: more economy, more resources. You are ahead in resources which means you can simply do more of everything than Protoss in every way.
So your response to this bizarre Protoss behavior would be: Prepare enough defenses to hold off any potential attack, and use all the rest to put yourself more ahead and guarantee a win:
When you're ahead, you don't need to take risks, and you should play safe because you can afford that luxury. Don't attack him until you are certain it will be A-move-to-GG.