I dont see a problem with it. You could def chop it if you feel the top is ready. that doesnt look ready, but like u said the tops tend to get done faster than the bottom nugs. Lots of people take the tops and then let the plant finish up. it might slow down growth for a couple days but its better than having one done bud and alot of underdone.
Also i trim lots of fan leaves off in my scrog. almost all of them. people argue against this but i think it warranted in my situation. i wanna smoke bud not fan leaves.