Does not compute. If the company writes it off their taxes, it's the same as the government supporting them directly, only instead of giving the money to organization directly, they're taking it out of what a company would have to pay them. Same net loss.
OK, so what you're saying is that you don't know how taxes work.
Company A makes US$15m. They donate US$50k to the OpenBSD project.
They report to the government that they made US$14,950,000 for the year. Income is then taxed based on that figure.
Do you know why that's how it works?
Because they effectively *didn't* make that money.
Now, if you want to argue over government policy regarding taxes for non-profit organizations, that's another debate.