I can't say for his personal ideas cause that's an elia question but in terms of the succession of France it is important to note: no matter how you slice the cake Edward III under any succession law could not inherit France, this is a fact. Isabella's reasoning ignores all of her brother's daughters in order to claim the throne, it is a weak excuse to claim the throne of France that's why she was thrown out. For this TL though, I think the best way forward would be agnatic-cognatic primogeniture since Joan is the granddaughter of the firstborn prince of France. For English interests in France though the key word I think here is that there are crown lands of France and there are the various duchies. Philip IV's death is going to spark major arguments with the estates, one of them is definitely going to argue Joan is illegitimate and the crown should go to Capet-Burgundy through the tour de nesle affair. Another argument lead by Charles of Valois or Philip of Valois is that he should inherit due to Salic Law applying to only the crown of France. If Edward successfully seizes the throne of France most likely through right of his wife, Joan II of Navarre he will spend quite a while getting rid of these succession claims after all, any Capetian branch such as Valois and Everux will challenge and consolidate their claims to take back the throne, I will also point out the crown of England was also not that powerful either after Edward III's ascension he only held the land by force of charm and arms. How this is going to play out we shall see, honestly I could pull a genius move and dissolve the crown of France