This whole "Coinbase doesn't have to talk about Ethereum thing" is just dumb. Of course, they don't *have* to talk about anything, but the incentives are already there for them to do so.
Coinbase is very incentivized to talk about Ethereum and see Ethereum/ETH do well - they own 137,000 ETH, are the third largest ETH staking service, are building their entire onchain business on Base (which settles on Ethereum) and have many investments in Ethereum-related companies.
It's not about "alignment" - it's about Coinbase (and other entities) being vocally bullish on the thing that they have invested a lot of time and money into.