If we implemented a Peakd.com for Bitcoin Cash, could this happen?
I don't understand what you mean. Bitcoin (and derivative) blockchains are not ideal for posting large amounts of data / text transactions. Why can't people just use hive?
It's also extremely hard to develop cross-blockchain interactions in a secure way.
Let me ask you something a little different then. Suppose some party had his identity linked to some bitcoin cash address. Couldn't a soft-fork be used to freeze his funds as been done here? I do think it could be. Making this impossible should be the goal of every future blockchain project.
The motivations for miners are different than that of Witnesses. No Bitcoin miner would feel threatened should the Satoshi coins start moving. They could still sell the coins for money and profit for electricity. For Satoshi to become a miner he/she/they needs to invest new capital into ASICs (unless he has one). The bitcoins Satoshi has doesn't let him generate new coins or control consensus.
Yes, but it would require a large portion of PoW miners to conspire to censor transactions. That's unlikely because censored users could also increase their transaction fees to tip the miner incentives.
This is more likely to occur on Bitcoin Cash than Bitcoin, because Bitcoin Cash is choosing a path of greater miner centralization. Bitcoin is God... for now.