The question is would there ever be such a multinational state even if Pilsudski would have gotten it his way and managed to be its leader. I don't know how genuine his words were but even if believing that he was sincere  saying that, I doubt his policies would follow up. His army's behaviour in Galicia and Volhynia after the suppression of WUR leave me in doubt about him being able to accept equality of Ukraine and Poland and, perhaps, others in the Polish-centered mega-state. His army's mauradeering in the central Ukraine during the PSW may not prove much, because it may have been common at the time, but he could have taken measures here too. The most important thing, though, is that unlike some Polish people I've seen believe, the equality of nobility and religions in PLC is a myth or at least it is a myth from what I read. It may be unprecedentedly "equal" compared to other multiethnic states, but other states never claimed to be "federations", or "Democracies of nobles". Other states never proclaimed religious freedom too and Warsaw compact was unprecedented. The truth perhaps is that the proponents of such federations throughout history always assumed a Polish domination there, even if subconsciously. I see no reason that Pilsudski was any different in this respect.