It seems like Kate is looking for someone to blame. But I don't think that a parent who gives their offspring advice, should be the one to blame.
This isn't Charles saying he won't accept Kate, its him basically telling William to be a man.
If William isn't sure by what 4 years, than he'll never be sure. And he really should move on.... Charles may have done Kate a favor...
And Charles advice is the type of advice an parent/close friend would give someone in similar circumstances.
Now, I thought Charles father telling Charles that he should make up his mind about Diana after only 4 months of dating, was incredibly ridiculous. But after four years, at their age it makes sense.