I mean, if we're going to be that vague, we can say the internet is relevant as a discussion topic because Dropbox's business relies on it.
The security of this one feature might be relevant, but the security of the company, especially in the context of a completely separate decision that isn't at all related to this product is, IMO, not relevant here.
My concern is that such a topic is going to dwarf the discussion of this feature, which is really what we should be discussing here. You can already see it happening; the comment thread is the top thread here, and most of the comments on this story are related to it. So while that shows people are interested in that particular topic and its implications, it's also by far dwarfing the real discussion topic for this link, which is the Dropbox Paper product.
> Dropbox's business is enabling users to share content.
It's worse than that. If sharing was their only business, as opposed to backup, storage of data -- then it wouldn't matter as much if you could trust them or not. If your intention is to share data, then that data shouldn't be considered as secure any more -- even if you trust the person(s) with whom you share it.
But as Dropbox does more than just enable sharing of data, trust is paramount. Without trust, docker isn't a service, it's a liability (I don't necessarily I think the addition of a pro-surveillance board member makes much difference for how much I trust Dropbox, I'm making the point that trust is/should be a core business value of Dropbox -- if you can't trust it, I don't see how you can use it (without engaging in doublethink).
Arguably, security is an issue for anything that contains user content. Dropbox's business is enabling users to share content.
I could see that the issue might not be appropriate everywhere but I think it's appropriate here.