while asleep yeah, good plan.
But you should also stand ready to catch kitty when he next tries to climb his tree/s... because he wont understand why his claws are not gripping anything.
Maybe soft paws cats get used to it and stop trying to use claws naturally for climbing and scratching (which is a form of marking for them) but I wouldn't know
Its also very easy to clip the tips of claws (few at a time and take your time) while kitty sleeps.
/edit
saw you put this:
'' I do trim his nail every week while he sleeps. ''
Does he calm down with the scratching after he's clipped?
if so just do it more often?
luvthatkittykat? your posts are very hard to understand by the way... no judgement just pointing out to you that leet speak(?) text talk will mean less people can read what you type.