I don't think it's a matter of what is "allowed", just a matter of the standard. It's been close to a decade since I've left the Western Hemisphere, but on the 737 (Guppy, 7-3, etc.) I've never had a problem when I said I wanted my meal before the pax, because there's usually a reason. On some trips (early departures on a short leg) the flight attendants will ask or even take the initiative to cook it before push because they know you need it early in the flight before the arrival. Long story short, whether pilots want to acknowledge it or not, customer service is very important and I like to go with the flow unless there's a reason to do otherwise. I think a lot of the push back from FAs regarding the timing of crew meals is how it's approached. Explain why you want your meal early and if the FA still has a problem, they can catch the next flight out... but I've never seen it come to that. On the pilots side, knowing the standard timing of meals, wouldn't it make sense to show up having accounted for that, just as you would show up expecting a certain break time? I think sometimes people show up looking to flex their muscles. For me, life's too short for that.

So true, but there are many who see it as their appointed mission to deny it.