I did encounter the same situation, selecting pre-flight a "book the cook" option, which also happened to be on the on-board snack menu.

On board, I got requested, when I wanted to eat my meal. Or so to say, by selecting the "snack" as a "book the cook" option, I got offered a flexible meal time. I went to sleep right after take-off and 10 hours later, I got my "snack" as the normal evening supper meal. Granted, I am DM, so that may have influenced the flexibility around the meal time.

To me, this does look like a positive development. A little bit moving toward QR, where you can select for your meal, effectively what is available on board, at a time that suits you. I can understand, not all meals can be treated this way, given the lead time it takes to thaw, prepare, etc.