The "tail gating" (That's what we call drinking in a parking lot before X event around here) was WAY out of line IMO. You guys were going to a brewery and were going to be sampling the beer inside. Do you bring your own steak to Red Lobster? No...There is a time and place for "tastings and socials". I personally would have been insulted if you guys showed up at my brewery and were drinking homebrews in the parking lot BEFORE the tour...After the tour, no problems. If you felt the urge to pull a beer bong out and shotgun whiskey in it that would be up to you...IMO you guys were WAY in the wrong and your club needs to put some guidelines/rules in place for your club "road trips and brewery tours" even if it is on a per trip deal. My club sends emails out to everyone and talks about issues just like this for when it is right or wrong to bring/drink homebrews so no one is "out of line" or feels that way.
Step back and look at it from the manager's perspective not only are you guys being "yahoo's" one of you may be a potential liability. I am not sure what was said specifically but I can imagine the talk when they said no one that has been drinking or smells like they have can come in. All the "but, but, but what if we" would also not have been good to listen to...I am sure they fully understand you guys came a long ways, as a big group on a bus it was right there...and why on earth did you not put on clean clothes before you left on said trip? have you no self respect or respect for the other people on the bus that will be smelling your stench? yuck!
This is where I change to "your side" they should have not given you the gift store employee when you paid for something more. This and this alone is the only thing that is working in your favor, IMO.
So now the tour is over, and you are still being scrutinized against/watched because of what has happened before the tour. In the manager's mind(s) you guys are "trouble". I have no idea what your club member said or did. I would bet it was a snide comment or one that was interpreted that way by an already agitated manager. The instant removal of said drink and yelling to get this person to leave may have not been handled quite right but most people do not react well when "being asked nicely to leave" this is why there are "bouncers".
The last thing to add is you did not tip your food server well because why? you guys were mad at the brewery. That person busted there hump, tried to make you happy and you slap him in the face. That is uncalled for.
I do not drink much of this breweries beers and this does not effect me in either direction. I am sorry you felt you had a bad experience but IMO 95% of this could have been avoided with some basic rules from the club. I hope you try to learn from this and not have a chip on your shoulder.