Any opinion can change over time. Some time ago there was a vote, and they voted against it. But what’s stopping them from holding another meeting and voting in favor, if global policy trends create conditions where it becomes more profitable to put Bitcoin on their balance sheet.Any entrepreneur is interested in profit, and they are definitely no exception.
Let time and chance do the deciding for them. Every business aims to make profit but that doesn't mean that they will not consider the risks involved in whatever financial decision they make. The reason they voted against Bitcoin 8 months back was because of its purported volatility index and that hasn't changed yet but it doesn't mean it won't.
Microsoft is a big company that no matter what time they choose to enter the market as investors, they would still make huge bucks out of it. Granted, it's better to start now than later but the thing is, it's still their choice to make.