The Liquid supply is provably linked to the proof of work chain, and Liquid privacy makes it basically impossible for them to target or censor any individual. The federation could collude & freeze everything (at the expense of their entire business model), but they can't censor or arbitrarily inflate. It's really nothing like Eth. There are always tradeoffs, Liquid is by no means perfect & no one is saying you have to use it, but I think blockstream is an extremely valuable bitcoin benefactor & will continue to be.
Discussion
None of the arguments you're making make sense because you've put tradeoffs to decentralization.
For example, why isn't Bitcoin's confirmation time a minute like Liquid's?
Because nodes need enough time to verify and propagate transactions and blocks. A one-minute block confirmation time would mean that only the high performing computers would be able to act as nodes, which is far from decentralized. Short confirmation times also lead to more stale blocks and a worse user experience.
The reason Liquid works and seems slightly decentralized right now is because there are so few users. Unlike Bitcoin's antifragile properties, Liquid is fragile. Eventually, it will become hyper-centralized, and as more Liquid users join, history will repeat itself, just as Gold became Fiat from the Nixon Shock.
To me, encouraging people to use Bitcoin properly and telling them not to use Liquid are the same thing.