There is a difference between "active" and "handling flags" (I don't believe I was even active in that period, for example).
It's my belief that everyone has their part to play in keeping the site "healthy", and whilst moderators are here to, well, moderate, we all make a difference - a down vote and a comment can be far more powerful to the poster than a moderator weighing in and deleting the post. Like all the Stack Exchange sites, there is a balance between reacting to flags, and encouraging/allowing the wider community handling the issue themselves (be it through high reputation users following through the review process (currently available to 8 users with more than 2000 reputation), or simply through commenting and/or downvoting) - if followed through in this manner, the system itself will decide to protect questions as required, as it appears to have in this instance.
This does also highlight an important principle for Stack Exchange sties, and that is we should all vote to reinforce good behaviour, to help reflect the reputation, and provide a larger group of people that can help handle the reviews.
One principle I always try to take on board in all my activity online, is borrowed from Wikipedia, and that is to assume that the post was made in good faith. In the example you've provided, it may be the case that new people don't quite get the idea of Stack Exchange, and they think it works like a traditional message board - a quick, friendly, comment can be a nicer way of handling a new user, rather than the comparatively silent approach of flagging their post.