Gonna answer your question at face value.
Sponsorships are generally acknowledged with quid-pro-quo advertising opportunities - otherwise they'd be called silent donations.
In the case of tech conferences like the inciting incident, that means your logo everywhere, maybe an ad spot in between talks, and booth space. You might get some intangible reputational benefits from whatever other sponsors are present if they are viewed as highly prestigious or respected. Might even have opportunities to do a talk by one of your employees, we've all been to conferences where a vendor conspicuously also has a talk that coincidentally features their products heavily. All in all, it can elevate your perceived legitimacy in various ways.
Advertising might get you more business or more applicants and thereby grow your reach and success.
In terms of my personal values I'm a pacifist. I don't want to see something I like(d), something I made modest code contributions to, used to advertise for a commercial military organization that manufactures equipment for violence. It's the same way a vegan probably doesn't want to see advertisements by the beef farming industry or that someone who cares about renewable energy and sustainability doesn't want to see sponsorship by someone whose holdings are a huge stake in coal mining and fossil-fuel power plants.
In the case of the inciting incident, it wasn't a case of massive dollar amounts, it was ~$5k USD and it wouldn't have jeopardized the conference at all to say no thank you.