Cass wasn't a man who couldn't listen, or even change his position (he certainly had when it came to Umbridge) but he wasn't sure Dolohov was as nice as Morag made him out to be. Then again, he couldn't blame her for trying. Most probably wouldn't think Percy was nice, or funny, yet he found him to be both.
'I will not be so presumptuous as to hold it impossible that I did misunderstood about my grandfather, nor will I argue with you on your husbands personality. I hope you are right, but I will leave it to him to prove you so, though even if he would prove you right I hope this job means dealing with you and not him. Percy trusts you, and as I trust him so do I to the same extent.' Which was far from completely, but he didn't add that, there was no point.
'And I'm glad you promised it would hold up to scrutiny as I do not hold for improbable that I might want my old job back one day should the situation ever be right.'