One can only speculate as to Kublai Khan's feelings about rebellion; however what is known of Mongol practice suggests that he would consider it not only justified but perhaps practical as well.
Kublai's grandfather had been Genghis Khan, (the name means "universal leader; his given name was Timujin.) Typical Mongol diplomatic practice involved personal courage in battle and intense loyalty to ones allies; however if one could improve his own position, he was expected to betray his allies or even his superiors. Genghis himself managed to build a substantial power base by securing allies and then suddenly turning on them. It should also be remembered that the Mongol invasion of Europe ended suddenly in 1241 with the death of Ogedai Khan, Genghis's successor. The Mongols obviously had no standard rules for succession, and all expected the ultimate power struggle; therefore they abandoned their conquest of Europe.
There is no indication that Ghengis Khan was any different in philosophy than his famous grandfather. Like all the Mongols, he was a fighter, not an administrator, and often chose local people or even foreigners to handle administrative matters. Because of their lack of governmental skills, most lands under Mongol control managed to free themselves within a century. In fact, when the Mongol capital of Khanbaliq was captured by rebel Chinese forces in 1248, the Mongols simply abandoned the city and returned to the steppes where they felt more comfortable.
So, although any answer must be speculative, it is perhaps safe to assume that Kublai Khan, as his famous grandfather, would consider rebellion--or for that matter any form of fighting--as quite natural and justifiable. Loyalty to the government was not a matter of Mongol concern. However, he also believed that any such attempt at rebellion should be ruthlessly suppressed; if for no other reason than simple survival.