These attitudes are like fads. It wasn't so long ago that it was hip to expound on how pointless FW was, how it could be likened to a 'bloodsport' held within a pre-defined arena, a proxy war fought largely by mercenary podders who care little about their employers. And indeed, there are still plenty of characters who think like this. (With a fair degree of merit!)
Now, after CCP revamps the FW mechanics and makes some vague hints about faction support having to be proven through actions in space, you're suddenly not a faction loyalist unless you're in FW.
Really, just play the game how you want to play it. I interpret Falcon's comments more along the lines of 'If you want to change the outcome of a live event, be prepared to commit/spend assets, and put yourself in a position where you can potentially suffer real losses.' I do not think he meant 'join FW or gtfo.'
It's fairly obvious that I find FW a lot of fun. But it's not everyone's cup of tea. And being a privateer-soldier isn't the only way to be loyal to a cause. Certainly, it's a valid tactic to, in-character, bludgeon someone over the head with their 'lack of commitment' as evidenced by the fact that they're not in a militia. But it's also a valid in-character argument to say that enrolling in a CONCORD-sanctioned militia with a bunch of bloodthirsty pirate capsuleers to fight a limited war is not the best way to serve your faction's interests.
Deploy whatever argument suits you in-character, and don't worry so much about other people's OOC attitudes or perceptions. Ultimately, it's a sandbox. Things like warzone occupancy will ebb and flow, shaped by the shenanigans of non-RPers. The effect the 'roleplay community' has on the FW warzone is actually really small. So just relax and write your story the way you want.