I imagine a large store could get a winery to do a joint project, but I got the sense that this person just wanted to do a small run for himself and maybe friends-and-family.
While I partly agree with you. The top post suggests that the person is looking for commercial quantities. Note this sentence: I want to but the barrels, package it, name it and distribute it as my own brand.
This person should be able to make a deal with any winery that can get the appropriate grapes, and it is not unusual for wineries to buy from other growers.
Without knowing the actual quantity desire, we are both guessing on this.
There are wineries and growers who make all their business from producing for others. It drastically cuts many costs and allows them to have a gqaranteed income, rather than hoping that people will like their wine.
While there are some do-it-yourself places out there like this one -http://bostonwinery.net/
They usually are fairly specific about what types of wines they'll help you make.
On the other hand, there are wineries that will let you take their finished product and simply custom label it -http://www.favorlabel.com/
for weddings and such, so that's also an option.
I believe that this person is looking to label some wine. That is possible with many wineries.