What is your understanding of the word "binding"?
Just what it means: "to impose a legal or contractual obligation on" as in, the Pope infallibly binds all the faithful to believe "x" as a matter of faith. Those that do not, are anathema.
Since V2 did not infallibly 'teach' anything, therefore their teachings are non-solemn and do not impose/bind the faithful to the same degree of belief as an infallible statement. I'll repost this quote, to explain. This quote is from 1935! Anyone think it's not orthodox?? (I broke out the quote with numbers...those were not originally present).
Since not everything taught by the Ordinary Magisterium is infallible, we must ask what kind of assent we should give to its various decisions.(1) The Christian is required to give the assent of faith to all the doctrinal and moral truths defined by the Church's Magisterium (there were no doctrinal or moral truths defined at V2).(2) He is not required to give the same assent to teaching imparted by the sovereign pontiff that is not imposed on the whole Christian body as a dogma of faith (nothing from V2 was imposed upon the whole Church as a dogma of faith).(2 b) In this case it suffices to give that inner and religious assent which we give to legitimate ecclesiastical authority. (this is why new-rome says we must give 'religious assent' to V2)(2 c) This is not an absolute assent, because such decrees are not infallible, but only a prudential and conditional assent, since in questions of faith and morals there is a presumption in favor of one's superior (under normal circuмstances, yes, we trust our superiors. Not in the case of post-V2)....Such prudential assent does not eliminate the possibility of submitting the doctrine to a further examination, if that seems required by the gravity of the question (Nicolas Jung, Le Magistère de L’Èglise, 1935, pp.153,154). (Yes, based on the gravity and confusion of V2, their "teachings" need to be further examined, for they are not infallible, nor clear, nor are they trival matters.)So, to sum up, V2 was not infallible, because it didn't define doctrine, and it didn't impose on the whole Christian body it's teachings as a dogma of faith (therefore it's not binding), therefore we ONLY OWE our 'religious assent' to V2, which is not absolute, but only prudential and conditional (notice "prudential" means prudence). Such 'religious assent' we owe mainly because the hierarchy are our superiors, (and are usually orthodox) yet we are still allowed to question the 'unoffical teachings' and further examine them, since V2 dealt with grave matters, which are related to our salvation. And most importantly, we are allowed to question them because time has proven that most of the V2 hierarchy's orthodoxy is highly questionable, which means that the council's orthodoxy is highly questionable. And this possibility that V2 is less-than-orthodox has nothing to do with indefectibility but everything to do with the ambigious, and inexact language which was used in the docuмents. Had the hierarchy wanted to define something and make it an official teaching, they could have. But they did not define anything, therefore, we can question the council and, hindsight being 20/20, we have the obligation to question it.