What is the point they are trying to make here? Has anyone ever argued that fossilization can't happen quickly? Is this person about to go into a rant about dinosaur fossiles only being 70 years old?
It's a strawman/red herring argument about the Noah's flood.
If a lay person thinks it took millions of years to form the grand canyon, well someone will point out that this rock/fossil/cucumber became preserved in days, so therefore all known fossils and geological formations too could have formed in the weeks during and after a global flood.
Fast fossilization is an interesting phenomenon. You can even clone things that were fast fossilized and they'll remember everything from their original life. However, your robot friend could become jealous and try to ruin everything if you attempt the cloning.
If the pickle was in a jar the whole time, where tf would it get rock required for fossilization? Cause I remember learning fossilization is basically just bits of the original material bit by bit being replaced by rock particles from the surrounding area.