I thought at first this was a slippery slope fallacy, but it's not exactly. The author realized the power that package indexes have and wants a different system

I thought at first this was a slippery slope fallacy, but it's not exactly. The author realized the power that package indexes have and wants a different system. Even suggests an alternative! This is a very different argument than "if they do this, next they'll do that" or "by doing this they'll have more power". People often mistake the exercising of power with its existence. Here's an example: In 2016 a huge amount of Ethereum got hacked. So much so, the creators of Ethereum decided to fork it, unwind the transactions and call that new chain Ethereum. The original chain is Ethereum Classic. An argument I've heard is that this was a bad move because it sets a precedent and "made the chain not really immutable". If something is immutable as long certain people don't do things they can totally do, then it's not really immutable. (Jeez I don't actually want to start a fork flamewar, just contrasting the logic. Fingers crossed).