Zvika,
Otzar BD officially keeps the wine at the zman Biur, especially wine that is intended for export, hence I don’t see where you concern is coming from.
Moreover, on wine/grapes that is grown for export there many other heterim, regarding Hotzah and Biur see, at length discussed in Ridvaz on Shmitah in the following link, wherein they did export wine :
http://hebrewbooks.org/pdfpager.aspx?req=7707&st=&pgnum=317
Personally, many hold its nowadays a rabanon (see above), and many hold the Heter Mechirah is in effect if done, although they would oppose doing a Malacha (planting etc) though a Mechirah and oppose the very Mechirah as well ואכמ”ל
But the fact is there was a Mechirah on all of Israel, so it would be fair to say you can rely on that regarding the concern of Biur only, where its facts are unknown and was sold via Otzar BD.