If the engine is running at a pretty high RPM, I can't image a suck injector would be able to supply enough fuel to hydrolock a motor...but who knows. I guess anything is possible.
Let us take another route. It is called "Thinking".. Not something you will find in your FB research.
The internet says an s55 injector from Kies (first result i found. Can be wrong) can flow around 22g/s @ 100 bar (1450psi). Let us just assume this is the max flow.
What is the remaining volume at TDC? I have no idea.
1 liter of pump fuel weights around 720 to 775grams. So 22 grams are around 30ml of pump fuel. So as soon you hit 1450psi or more you are constantly injecting 30ml of fuel into your combustion chamber. Yeah. Most will leave unburned through the ex valve. But only so much possible.
Now.. Why do you assume high rpm? Hydrolock and stuck open injectors are not a thing during high rpm. This can happen any time. It happened most likely happened when hitting WOT and fuel was just filling the cylinder.
My guess with thinking about the issue is.. It wasn´t high RPM but if an injector failed and was stuck open it is ALWAYS injecting fuel without any PWM operation.
Now.. Still something you can´t imagine?