The Saudi government is the most repressive on earth except for north Korea. They are literally worse than iran.
When they pay for things, they aren’t being an loyal ally. They are hiring us.
Saudis keep their friends close, and their enemies even closer.
That depends on what your gauge of repressiveness is. As to hiring us, it's good to be paid by the Saudis for services that we would have provided anyway - namely keeping the Soviets out of Africa and South America, and preventing any one Muslim leader from unifying the oil resources of the Middle East under a single ruler.
Whereas we are obligated to provide free protection for "allies" in Europe and East Asia. There's a word for people who provide free services. Slave. We are slaves to military dependents like the NATO countries, South Korea, Japan and the Philippines. Better to be an employee than a slave, any day of the week.