Being open to use by and even receiving code contributions from various sectors is primarily a code licensing question, and can’t really practically be forbidden under a traditional OSS model anyway. Use of the tech is not the same essential thing as the sponsorship relationship and the latter is not something anyone has been guaranteed or should feel entitled to.
Thus, providing a platform and an audience to organizations (as part of the quid pro quo expectations that are informally attached to most sponsorship agreements) should be considered separately than “would we reject their PRs”. As an end user I personally don’t really want to be advertised to by arms tech, since I’m a staunch pacifist and I recognize that “defense contractor” is generally a euphemism used to substantially downplay the ramifications of what they do and what they sell.
I likewise believe that if I were a vendor considering a sponsorship commitment, I would also want some transparency and clear guidelines about who my logo and reputation might be sharing a literal or metaphorical stage with. Palmer Luckey of Anduril has some exceedingly fraught behavior that I certainly wouldn’t want associated with my hypothetical brand even by implication. I wonder how many of the current or potential sponsors have had concerns there, if any.
We should also consider which people are being made to feel unwelcome and unsafe by the event organizers embracing companies that explicitly work to make current and future violence more effective and more deadly, since it may be not-so-hypothetically applied against themselves, or their family members, or their homelands in the future. One can argue to be impartial for impartiality’s sake, or take the rather flawed stance of “let’s be ‘apolitical’, this is a technology-centric space”, or even focus on “what kind of good can we do with the [blood] money”. It’s simply not apples to apples versus other sectors that may be subjectively disreputable, when “this technology made us better/faster/more reliable as a company” has a direct connection to literal warfare.
To come at it from a different angle - what would the foundation and more importantly the ecosystem miss out on by not accepting money from/providing a platform to anyone willing to open their checkbook? What would be needed to keep things moving along sufficiently without having to make deals like this one - twice in less than a year?