Since the start of NXT WWE has held many tryouts at the Performance Center looking for the top young talent on the independent circuit. Since then they have signed a various amount of top independent talent like Uhaa Nation, Kevin Steen, El Generico, Adrian Neville, and many others. To my knowledge nobody has turned down the ability to attend a WWE tryout. However, that was until the WWE invited the Young Bucks to a tryout and the Bucks turned down the offer.
Now the WWE seems to be bitter about the fact that someone actually turned down an offer to attend their tryout. Though people believe that the WWE wouldn't be bitter about and just because they used the term "Young Bucks" in Mark Henry's promo a few weeks back and titled an episode of WWE Fury: Superkick Party means nothing. (The term super kick party is very often associated with the Bucks because they are famous for Superkicks)
You may believe that and your entitled to your opinion but just think about it like this, when was the last time someone turned down a WWE tryout. Like I said above I don't ever remember someone turning down a WWE tryout chance, so is it possible WWE just doesn't know how to handle someone saying No to them it's possible. Just think about it the Young Bucks in WWE, how long would it be before they weren't a team anymore.