This is a great start. My initial thoughts are these:
- Under Governance Structure, I would alter Indicator 1 to go beyond the binary True/False and include the consensus protocol in use. Several blockchain-based social media platforms utilize DPOS, which is more centralized than pure POS, and certainly more than POW. The decision-making process is still distributed, but it's not as widely distributed. It's like the difference between a pure democracy and a democratic republic. I'm not saying the pure democracy (or POS) is more desirable than the other, but if the goal is to measure decentralization, you'll get truer results by drilling down to the purest metric.
- On Node Distribution, I'd add how easy it is to establish a node. Is it cost prohibitive most users due to expenses or technological hurdles? If the ability to start a node is prohibitive to 80 percent of the users, then some of the other factors are moot.
- On Token/Wealth Distribution, there should be a measure for whether tokens are set aside for a governing, semi-governing, or development entity. For instance, was there a pre-mine? Is there a separate account for an "overseeing" entity that receives some of the token distribution at any phase of the project's life? In Steemit's case, this indicator would have been a 1 as that directly impacted what led to the Hive hard fork. Other projects have similar set ups where a portion of token distribution is set aside for development, which is controlled by an entity apart from the blockchain.
Otherwise, this is really stellar work. I'd like to see it developed some more.