There’s nothing inherently wrong with eating late.
Not doing so is usually given as general advice for a few reasons:
- Digestion can prevent you from sleeping well
- Excess carbs before bed pretty much all get turned into fat cells because you’re not going to use the available energy while asleep
- If you’re too full when you go to sleep, you may not feel like eating much in the morning and it can throw off your dietary routine
If #1 doesn’t happen to you, then a shake after a workout isn’t going to hurt you at all.
The net effect is not the same, specifically because of that simplistic view.
OP is trying to cut. Generating extra fat cells works against that process - even if he ends up using the energy stored in those fat cells, the cells do not die off - they remain and add a layer of adipose tissue between the muscles and skin.
It’s not something most of us worry about very much, but for someone trying to achieve a lean look, it’s undesirable.
CICO is “bro science” that works for the vast majority of us, but those minutia you’re glossing over are actually important in this scenario.