It is well known in fund raising most people who say they would donate will not donate. And anyone can give Mozilla Corporation money now by subscribing to their services.
I'm not sure this is exclusive to fundraising - the same is said in business about people who will actually purchase a product, versus those that say they will. Regardless, the comment felt unnecessary in context.
And for what it's worth - subscribing to services is not really the same. For one thing, it puts a cap on how much I can (reasonably) provide.
