#1, I think I feel bad for the goldfish. They require 20 gallons for the first fish, and 10 for each additional one. So, unless it's a 70 gallon tank...they've got trouble. And they're going into a smaller one? No water change in 6 months!? Hopefully you can share with them some of the info you've learned here, and teach them how to care for their fish.
Second, assuming the media stayed wet and the tank was healthy, it will be perfectly viable. That said...those Goldfish are going to suffer tremendously if you take all the media. The bacteria in those filters is their only saving grace, and the new tank they're going into will be completely uncycled and is going to be an extremely bad situation for them. Personally I suggest you return the seeded media, and maybe only keep a small portion for yourself.
Here's a link you can give them...in fact, you should link them this entire website-
http://www.aquariumadvice.com/articles/articles/124/2/-I-just-learned-about-cycling-but-I-already-have-fish-What-now/Page2.html