They might indeed, but the person filing the bug report in question (in their capacity as a user of PHP, at any rate) is not a customer of Yahoo! Inc., and thus Rasmus' employment there is irrelevant to the point at hand.

That point, rhetoric aside, is that the reporter is not party to a commercial contract with the people who fix bugs in PHP, whoever they might happen to be. Consequently, there should not be the "trouble" that moconnor asserted would occur should anyone in his organisation respond to a customer in that manner. The two parties simply do not have that relationship.

The phrase "unpaid volunteer" comes from Rasmus himself, in the bug report under discussion: "Wow, a classic case of how not to treat unpaid volunteers who provide critical pieces of your money-making infrastructure."