Peter appeals to Paul as confirming this same truth. That God is delaying His return because He is longsuffering. However, he does not say impossible to understand. They don't know, or don't want to know the basic principles of hermeneutics - interpreting scripture. It seems these preachers don't make an effort to get it right.
Good teaching is work.
They're untaught . Emotion driven, volatile. Used only here in N.T. to wrench, torture, to warp. These people are twisting Paul's own writings to support their heresies. They force scripture to fit meanings it was never meant to.