Twitter could avoid this sentiment by making a fiscally-binding statement:
"We have opened up our API, and have placed $5B in escrow with the Gates Foundation, who will return 70% of the investment income to Twitter. If we deny API access to developers before 2020, the Gates Foundation will keep the principal."
Someone sufficiently clever could make a similar, but perpetual, statement.
You could use equity, which would be really interesting, because the market would revalue Twitter based on the probability of them reneging and diluting the existing shares.
"We have opened up our API, and have placed $5B in escrow with the Gates Foundation, who will return 70% of the investment income to Twitter. If we deny API access to developers before 2020, the Gates Foundation will keep the principal."
Someone sufficiently clever could make a similar, but perpetual, statement.