A social impact token would be used to reward engagement and participation in a bifold way:
Commenting and thus co-ceating impactful projects-to-be would rewarded.
Participation itself is an impact goal and would thus be a trigger to distribute social impact token.
I'm not quite sure, what you mean by 'financing' the social impact token. The challenge we see, is making the token valuable. This will be dealt with by making it something desirable, as a means of payment, as a symbol for being part of something meaningful, by giving you voting rights. Our ideas could be decribed as Steem-plus - the plus being a value-based framework which replaces purely subjective curation by impact-oriented curation-mechanisms.
That's the challenge with all tokens, what ACTUALLY makes them valuable as opposed to just throwing a monetary value on them.