Nelson, for all that he was a raving egomaniac and a fully paid up member of the Awkward Squad, did at least have considerable gifts of leadership; the band of brothers he spoke of was not merely propaganda, he did have the genuine affection of a large majority of the middle and lower ranks of the Navy.
Suffren, although skilled, determined and persistent (and in all probability a better sailor in the purely technical sense), led by the shouting and bullying school- he had no charm worth speaking of, his command style was brutally abrasive, and he seems to be much more popular now than he was when he was alive.
He would likely be utterly out of temper with the revolutionaries, a son of the ancien regime at an age where most people's attitudes and sensibilities have congealed; even if he was willing to serve France regardless of who ran it, they would have looked on him with suspicion.
Fifty- nine is not an unnaturally early death, either- Cuthbert Collingwood died at 61, for instance. The most probable fates for him are, I reckon, in descending order,
arrest and execution as an aristo;
service with the Revolutionary French navy until he annoys someone important enough to successfully denounce him for incivisme, at which point, off to sneeze in the basket;
fleeing into exile personally, probably not to Britain- perhaps Malta where he would be welcome, at least until 1798;
somehow surviving in Revolutionary service long enough to take part in the early campaigns of the war;
escaping and being offered command of French Royalist forces.
I don't think forced is the right term; considering his initiative and reputation, the poor sods under his command may have to be forced to accept him.
He was good, no question, but he was also severely grumpy, and in the unlikely event of his putting up with the revolutionaries and their putting up with him, I'm not convinced he or anyone could overcome the largely self inflicted logistic and personnel issues of the French fleet of the time.
He would be making do with standards of provisions, powder, sails and rigging, dockyard support and above all crew discipline and training that the French Navy had left behind in the days of Louis XIV; standards that only started to pick up again after several defeats had hammered the message home.
Problem is that it's precisely those early defeats, nigh on inevitable with the Navy in upheaval, turmoil and shambles, he'd be being asked to preside over. Would the Expedition of Ireland, for instance, have been a success with him in Villaret de Joyeuse' shoes?
He would probably have been more use in naval administration than at sea. Again, if the Paris politicians could tolerate him, and he them.