You're right on the money...that's the part that often gets overlooked. It means the margin between quorum and overrule is slim...allowing dissenters to walk out to avoid cloture.
The more philosophical import of this is that it provides DISincentive to continuing discussion and debate. Our Senate is supposed to be deliberative, but this rule change made it a smart move to leave the Senate to get your way.
RULE VI
QUORUM - ABSENT SENATORS MAY BE SENT FOR