The Right to Abstain
A quorum protects the rights of absentees: For groups that require in-person voting (like the Business Meeting), the concept of a quorum, or the minimum number of members that must be present for the body to legally do business, protects the rights of members who are unable to attend. The requirement is meant to prevent a tiny minority from taking action in the name of the entire body without a representative number of members being present. For many (not all) US legislative entities such as the House of Representatives and Senate, the quorum is a majority of the total membership, but that's generally too high a bar for ordinary societies*. The quorum usually should be set to a number that you can reasonably expect to obtain in ordinary circumstances. WSFS has a remarkably low quorum of only twelve members, which is actually lower than the fifteen members that Westercon requires.
There is no quorum required on a vote of the entire membership by ballot: When you send ballots to all of the members, including the non-attending members, and give them the opportunity to vote on a given issue (yes, you can assume electronic voting if you like; let's not get tangled up in ballot-collection mechanics here), then effectively every member is present, and a quorum requirement is moot. There are no absentees to protect.
The right to vote includes the right to abstain: I'm aware that there are systems that require every voter to state a preference; I hate them. Sometimes you simply don't care, and I don't like people being compelled to vote. I want the ability to vote, but I don't want to be forced to do so. Any system that requires a minimum number of votes in favor in order to pass a given issue effectively makes abstentions (which should be Nulls and count neither for nor against an issue) into "no" votes. I think that's wrong. Imagine a Business Meeting with 150 people present and a subject comes up for a vote on which 149 of the members honestly don't care. One member votes yes, nobody votes no, and everyone else votes not at all. The issue passes 1-0. And it's irrelevant and a waste of time to "call for abstentions," because when you do so, people who say nothing abstained just as much as those who call out when asked.
There are special cases, such as roll-call votes where members vote "present" if they have neither a yes or a no vote to cast, and sometimes you actually do need to record this in case you have a quorum requirement that obliges you to show later that there actually were the minimum number of legally-required members present. You'll see this in small councils and in cases where members have conflicts of interest they wish to positively show they are avoiding by recusing themselves from the decision. However, those edge cases don't apply to situations where every member of the voting body had a reasonable opportunity to vote, even if most of those people chose not to do so.
Even with the increased interest in the Hugo Awards, a majority of the members do not vote. That doesn't make the decision of those who do vote invalid. It means the people who aren't voting are saying, "I don't care; the rest of you can decide for me." I would apply the same principle to any requirement that the membership as a whole ratify changes to the WSFS Constitution.
*Among other reasons, most legislative bodies have the right to arrest their own members and compel them to attend meetings, a right that ordinary societies lack. This is why some states whose legislatures have higher-than-majority quorum requirements can be legislatively paralyzed by the minority party boycotting meetings and high-tailing it for the state line. The Texas Rangers have no authority to go arrest legislators hiding out in Albuquerque, for instance.