Consider your self lucky that you could not post to that inferno that is now closed, not this site's finest hour.
I market and promote film by showing outstanding work made with it, handing out business cards that allow people to contact me about workshops, fine art prints, etc. I am always positive about film because I have reason to be, it has evolved into a wonderful niche.
But what I see on this site sadly more often than not and especially in this section is how *not* to promote film. You don't promote film by criticizing those who now use digital by making them feel stupid for their choice. Real photographers know that digital has been around long enough that it too is a mature medium in which to record an image. I happen to use and enjoy both for their strengths, have been making excellent images with both for decades at this point. I choose camera systems that make it easy and fun to use both film and digital together as a whole unit of highly flexible vision.
You also don't promote film by constantly picking apart and trying to figure out what film companies are doing or constantly chastising them for what you alone think is wrong. If they are making film and you can still buy it, why on earth would you criticize or over analyze them to death? All the photographers I know who use film simply do not do this, ever. I sure as heck don't and I warmly welcome any and all makers of film, paper and chemistry products, am very grateful to have them in 2015. To bash any film maker on a site like this or to a potential user of film is off putting, you will never gain a film user by doing that.
You promote film by taking charge of the grass roots aspect of getting people excited. People buy drones or GoPro cameras because of the work they see being done with them or the excitement it brings people in online communities like social media or places like this. No one in those user groups would ever be critical of the companies that make those products because they are not taking out full page ads in glossy magazines or appearing on billboards, the products sell through the momentum of use within the user base.
Same with film folks, it is really that simple.