I hate to be a wet blanket, but this is just another example of slacktivism.
Slacktivism is kinda like 'everyone turn your headlights on during 9-11 to symbolize' etc.
No real effort is required, just a couple minutes flying different in a video game.
If you want to do something special (and you are in the US), examine how you feel about this country and determine if it you feel strongly enough about it to put up a flag. I'm not saying it will cure hunger or cause world peace, but it seems that it would be someone more meaningful.
Please note, I'm not just saying 'put up a flag'. Only do it if, on reflection, you realize that you feel strongly enough about this country to do so.
People in other countries can probably find similar things to do that are appropriate for them, but in the grand scheme of things, 20 people flying their virtual airplanes together for 15 minutes (with the associated firefights that will start when newbies/jerks show up) is really not that big of a deal.