I would not condone the cabin crew's attitude in any way
.... but ....
even if I had not listened to the preflight announcement which probably included the flight time and had forgotten to look at my watch when we took off, it isn't difficult to guess that the flight would be 'about' 1 hour and then be able to guess the arrival to within 10 minutes or so.
Is knowing it to any greater accuracy than that really that necessary, personally I would doubt it.
Cabin crew on short sectors like that are usually pretty busy, and taking up even a couple of minutes of their time can seriously disrupt the service flow.
I think you need to take a chill pill.