I'm not familiar with how these cases work outside of the US, and I personally LOVE the idea of this buy-in coin, but...
Could this hurt your case, in terms of the settlement? A judge may be reluctant to issue a large sum, since ANYBODY can buy in to the payout. What would stop Google and Facebook from getting a bunch of these coins, and having the settlement go right back to them?
The SUFB token only represents 25% of the damages of those that have signed up for the class action. That's about $1 Billion in claim so far.
The vast majority of damages goes to the victims so Facebook buying SUFB tokens would only be a very minor hedge.