Aeration is a known factor in cocktails, it also requires some kind of protein or structure in the liquid to hold onto air for more than a few moments.

Which is all you need to change some components like those found in fresh citrus oils.

Slurping a bit as you sip will impact the taste more than shake/stir (assuming equal dilution, temperature, and clarity)

Shake is almost certainly creating more dilution though. You can’t handwave that away though it is unrelated to “bruising”

The other factor bruise-truthers trot out is Volatile Organic Compounds and the “top notes” evaporating out or oxidizing and I’m sure that would happen if you left a neat glass out on the counter for half an hour,

Im fairly positive that is why we can smell things and I believe your assertion that leaving a glass of gin out for 30 minutes with a much greater exposed surface area will lose taste faster than innthe bottle