Nonprofits doing brand promotion will sometimes value something like this for more than the cash donation value. Ie, if Amazon were to put Go GoldŽ on a bunch of their boxes, or a big go gold symbol on a plane and get earned media, that's valuable. Notice the R, this is a registered trademark to this nonprofit not just a slogan to fight cancer. The nonprofit may hope to use this brand to generate fee income over a longer time frame - so they need to try to make people aware of it in the first place to get the brand going.
If you are seeing it here as earned media (not a sponsored post) expect to see a lot more "go gold" showing up in the normal news (free marketing) in future - probably a big push about to happen - the plan is working!
The AARP is probably one of the better brand marketers, they did $880 million last year for the use of their logo's alone to give you an idea of how valuable building a nonprofit brand can be. Not tons of money but not chump change.