If it's a registered non profit you can donate and 'write it off' too. The idea that a 'big company' should do the donating is short sighted. That big company is made up of individuals. If everyone reading this donated $100, the problem posed by the article would disappear.
My point is that it's probably easier to get a company that is turning a profit off of something to donate a single large sum, than to convince a million people to donate $1.
If your effort is half as good, you still get half million people to donate $1.
On the company case, one million is not pocket change, so this will be a serious decision that has to be approved by several independent branches within the organization, each with veto power. Screw one of those and it's a deal breaker.
Furthermore, I'd say that this decision is one that is particularly difficult to frame for the company. While corporations do understand direct costs very very well, they are practically hardwired to ignore/exploit the gift economy. So the discussion will be stirred towards what indirect benefits will the company receive from donating to a worthy cause (public relations, tax exceptions, etc) and away from the consequences of letting a (unacknowledged) strategic partner to go under.
Not to say that a corporation cannot assume stewardship of a distressed project, but it almost always requires executive fiat to get over the bureaucracy.
It's easier still for a business to pay for a support contract, contributing to Canonical's revenue. Perhaps they could send a small fraction of that money to projects like GPG.