I can see potential ambiguity in hashtags and wouldn't apply my argument carte blanche, but this specific instance doesn't have any confusion in usage.

My main concern here is that the positions are often reversed -- in this instance a company used an individual's content in a friendly, appropriate way, and did ask permission before any standard commercial use. Usually an individual is using a corporation's content in a friendly, appropriate way and is forced to desist.

I'd rather see more sanity in IP rights and look at specific instances than broadly apply some one-size-fits-none legal interpretation. I'd also rather the discussion be about practical concerns in (public) sharing on social media; any image tagged with popular terms and public is out of your control regardless of IP enforcement. My point is more that the chain of events is predictable and will continue to happen, so rather than attempt to enforce a virtually-meaningless copyright on a photo tell people this is normal and be mindful of what and how you share your content.