Bearings and compression

Nil...

The procedure followed was correct:
Remove spark from the suspect cylinder to see if the knock goes away while engine running. Goes away, rod.
Two adjacent grounded plugs and goes away, main.

I never heard of compression checking for diagnosis of rod knock.

REaching a bit tooooo far into the theoretical there.
You will get a knock with a few THOUSANDTHS of excess clearance letting the oil wedge dissipate.
Only when the bearing is totally disintigrated will you get 1 or 2mm clearance, and one heluva knock. By then it's so obvious something is wrong, pulling the plug is thenext step, and then shutting it down till repair is completed.

Not taking a compression check.

Seen that too!

#1 bearing big end totally GONE and the enigne RAN...

A sticking lifter or valve would have NO difference when the power stroke was eliminated AT ALL---therefore I still don't see how a knock that diminishes with the removal from spark to the cylinder would be anything other than rod knock...

If there are other noises, pull more cylinders and see if it diminishes. The main is right nexct to the rod, and if particles flowed or flung into the next place.......

But springs, vlaves, lifters don't care about spark being present in the cylinder, and if he noticed ANY reduction I would rule out them as anything to worry about at this juncture.

Thatit decreased AT ALL when the plug wire was pulled is a BAD sign, and one of IMPENDING BEARING DOOM!

The more reduction in noise / knock you get when you pull the plug wire, the WROSE SHAPE the bearing (and journals) will be in at teardown!