The game already has so many exp boosters, that I find it next to impossible to gain levels without something in effect that's helping. The options to skip are also there if a new sub is willing to put forward some extra dough.

This is also going to sound like a broken record, but this game isn't WoW. It's not FFXI, EQII, or any other mmo out there. It would be wise for your friend to be made aware that even after catching up, there is no avoiding progression being gated by the story. We all go through it. If your friend wants to get through the levels even faster recommend to him/her to play a tank or healer to speed up queues. If you already have either of these roles yourself, then you can greatly help by joining your friend in the queues. Even if you go as DPS, it still helps a lot.

In short, old content is still fresh content to a new subscriber. Let them proceed and enjoy the game at their own pace. The road to endgame is only a problem because we make it so. If your friend just wants to skip everything so they can join you in mindlessly grinding tomes and tokens until the next patch, then this game might not be for them.