Guehi is a world class player. Howe is not an idiot, he has been clear that he only wants players who will significantly upgrade the first team not squad fillers.
Guehi is worth 75 million, in four years time he will still be worth 75 million.
Parish is smart but fair, if the deal works for Palace he will facilitate it, if it doesn't jumping up and like a two year old having a tantrum won't change his mind - it only makes the club look small time