They didn't do so unilaterally. The users of Ethereum collectively chose to bail it out.
A majority of eth miners and users decided to change the rules and ignore the promises of immutability previously made to all.
Having a majority does not make an action ethical. Hence the term: tyranny of the majority.
This serious breach of faith soured many people on the project, and the mis-trust continues to this day.
Pricing is not "tyranny of the majority." If nobody wants to buy what you are selling, you are not being oppressed.
Given that people decided they would much rather buy the coin with the altered ledger, it is more valuable.
As a meta note: Crypto seems to bring out the most low-brow critiques on either side. Maybe because it has become popular with a mass audience?
I don't see how ethics plays into it; it's a judgement call and the existence of the forked Ethereum isn't an attack on ETC.
> On 15 July 2016, a short notice on-chain vote was held on the DAO hard fork.[8] Of the 82,054,716 ETH in existence, only 4,542,416 voted, for a total voter turn out of 5.5% of the total supply on 16 July 2016; 3,964,516 ETH (87%) voted in favor, 1/4 of which came from a single address, and 577,899 ETH (13%) opposed the DAO fork.[8]