Having too much wine, as he said, "is a good problem to have." It's not life or death. It's not even close. But it's still a problem, and that begs the question: Is this really a good problem to have?
From a practical perspective, Walter was in an untenable situation. His walk-in locker at the storage place was jammed and crammed from floor to ceiling, from front to back, in a jerry-rigged 3-dimensional game of Tetris that kind of works in the sense that it all fit, but when he needed to get a particular bottle for a dinner, it was a half-day commitment. Sometimes he would sheepishly apologize and bring something that was closer at hand. And if you can't get to a bottle, what's the point in even having it? And, to some degree, he started looking back at his wine collection like I look at my old vinyl record collection. I used to love Punk Rock when I was in my 20s. Not so much anymore. Tastes change. I don't hate Punk Rock now, but I don't choose to listen to it very often.
Taking all of this into account, Walter did what a serious person does: he got out the actuarial tables and recalculated his forecasted wine consumption. He reckoned he could get by with a mere 1,000-1,200 bottles. He decided to downsize his collection substantially. This is sometimes indelicately referred to as a "cellar dump", or "weeding out". For solid citizen Walter, this was "taking stock."