How long has J. Lambert already been in charge of JLC? And has he been hindered to develop JLC over the years through internal requests/decisions of Richemont? I would have my doubts whether this was actually the case.
A suitable comparison is IWC. In my opinion, G. Kern has achieved significantly more at IWC (even if some IWC purists are rather critical of this) than J. Lambert in all these years at JLC. For a long time as CEO, he has not managed to give this magnificent manufactory with "tons" of substance the necessary emotional component that is essential for desirability today. So why should he achieve it now, when in a sale basically "only" the owner changes.
And all this at a time when the sale of luxury watches is more likely to be on the move in challenging waters. If Richemont actually wants a sale, I would find that rather unfortunate at this point in time. The brand needs a management that understands and can stage brands above all. They have endless watchmaking competence already. A hipp story is missing.