not really, you actually ruin there plans if you join the imperials because they have marked Ulfric as a dormant asset which means him winning the war would be playing into the thalmors hands and indirectly working for them. while the imperials have them following there every location they also are against one another. there are a few texts ingame that prove what i say the most informative being a journal from the quest called Diplomatic immunity.
the same dossier also said he wont communicate with them and is extremely uncooperative and he seems to hate the thalmor alot. The legion are weak , all cicero's journals tell that chorral is in a turf war between two skooma dealers and bravil was ransacked by bandits , also there is a journal that is in the battle-born manor that is signed by general tullius to kidnap one of the gray-manes , allow the thalmor to torture him for information while everyone pretended he was dead , what sort of empire allows that ? , i realise there is a whole "better in the long run" attitude but during the cease fire arrangement in the main quest if you didnt pick a side , the empire can't discuss their war with the stormcloaks alone , the thalmor have to be there while they make their decision so they can make it for them , ulfric and galmar refuse to negotiate until they leave and force them out , the empire may be stronger but being strong means jack when your not willing to fight , the stormcloaks if they win get straight to defending against the suspected thalmor attack , they know what the thalmor are doing but they also know the empire is just gonna continue to twiddle their thumbs and allow the thalmor to dictate their decisions , the thalmor are not so high and mighty either , they are not incredibly strong , they had to call a truce as well as the empire in the great war and they started the war on the empire with a surprise attack , the empire were caught off guard , sure that promotes the strength of the empire but they are trying to rebuild and its clear from cicero's journals they are failing. They are just using the empire to fight another war while they rebuild their army so they can weaken both skyrim and the empire and sweep in and claim both easily and then probably turn their attention to hammerfell.
Most importantly the thalmor dossiers states that both a stormcloak or empire victory is to be avoided [Oldenemor also says the truce is only until they are strong enough to finish off the empire]. This backs up the point they want to use one to wear down the other and when they are both weak , sweep in and take em all. Either way , best option is to pick a side and finish the war ASAP .
stormcloaks take the fight to the thalmor and don't give them a chance to strengthen their army whereas the empire would be stronger and more able to fight the thalmor and push them back but i dunno if they have the balls anymore which Ulfric does. So both choices are best to fight the thalmor just once you do it ASAP , just comes down to who you think has the brains to beat them and personally I think Galmar is a great tactician so I would side with stormcloaks .
This was all in relation to the quote , I know it had nothing to do with OP
