People who defend capitalism will point out that "well there is some market inefficiency (government interference, authoritarianism, subsidies) that actually makes this not real capitalism". In this example Saudi Arabia is a monarchist petrostate spending government money on stupid projects, so that's actually "not capitalism".
This is the same as the meme of people saying "not real communism" when someone asks how they feel about Lenin murdering a bunch of people.
Instead we should understand that capitalism is about private ownership of property, NOT a fictitious "Free Market" as Milton Friedman tried to re-center the conversation around. Understanding that capitalism is about ownership, and not markets, makes it clear that authoriatrianism and capitalism go hand-in-hand, as a strong and violent government exists to enforce the property rights of the owning class. The power structure of Saudi Arabia is fully compatible with capitalism as it exists throughout the "west" or the "free world".