The state assembly of California maybe sees things differently to you.

They believe they implemented the Roosevelt policy when it was presented rather than take  stand against it therefore were complicit. That is one reason why they probably apologised. Anti-Japanese sentiment was very high in those days so we do not know which sort of pressure the state of California was under and from which angles - but if they are complicit it stands to reason they should apologise.

The state of California was already discriminating against the Japanese as far back as 1913 when they passed the Alien Land Law to stop them buying farmland and 7 years later in 1920 they passed a law to stop anybody with Japanese ancestry from buying farmland so maybe they were not under pressure from any political angle and instead were happy to implement their racist policies before, during and after the second world war and if that is the case then again an apology from them to their victims is probably something they wanted to do: https://www.pressdemocrat.com/news/10732322-181/california-apologizes-for-japanese-american