1. People are retarded. What they tend to use to measure strength means jack shit. You lift to get stronger, not measure your real world strength against others. Your whole article is based on using squat strength as a measure of strength, saying they have equal relative strength.
2. I highly doubt anyone who puts on muscle and stays at the same bodyfat percentage is jumping lower. It may not be as drastic as they expect, but squatting does indeed help with one leg jumping. If they are jumping lower, it's because they got squat obsessed and forgot you need to jump a lot as well.
3. Again, xx increase in squat =/= xx increase in strength
You're completely missing the point and I'm just repeating myself, so that's it.