Yes, and no.

The riots which took off were no insignificant disturbances. LAPD had two immediate problems. One was the matter of protection of the officers. It's all very well showing up in Koreatown in the middle of a riot, but a badge and a pistol is more of symbolic protection than actually capable of dealing with a substantial part of the city which is rioting. If they weren't going to have a reasonable chance of effectively stopping the riot, they shouldn't try, until they have the resources to do so.

The other question is applicable to that of a firebreak. If there is already a massive conflagration which you can't quickly put out, it makes sense to put your assets somewhere else to stomp out any other fires which may start up before they become big fires as well. In this case, this means abandoning a lost cause while gathering the required strength to deal with The Big One. So, yes, wealthier areas of the city did see a stronger police presence than Koreatown. Most anywhere else in the city saw a stronger police presence than Koreatown. There is no reason to believe that this was out of 'protection for the wealthy' (even if it was, it's not reason to believe it), it is simply effective use of assets.

To give an idea of the scale of the riot, in addition to the 5,000 LAPD officers, they also brought in 1,000 deputies, 950 County Marshals, 2,300 CHP, another 1,000 Feds, and about 13,000 military personnel, complete with assault rifles and armored vehicles.

With reinforcements almost four times the size of the LAPD presence, it becomes evident that LAPD would have been taking something of a risk going into the heart of the riots right off the bat.

Certainly, the length of time it took to get into Koreatown once the reinforcements showed up has been criticised, but that sort of force structure doesn't show up as soon as the rioting starts. It took a full six days before the riots were done, with a death toll of 53, six of whom were shot by law enforcement, two by the military.

The lack of police protection in Koreatown led to several 'lessons' which are still observed by commentators.

Firstly, it was reinforcement that the police are under no obligation to protect you, an individual. (This has been caselaw since at least 1981, Warren v District of Colombia). Secondly, it is viewed as an affirmation of the utility of personally owned firearms for defense, the images of the Korean owners on the rooftops with firearms being commonly distributed. Finally, it's used as an argument against the ten-day waiting period for firearms purchases. A lot of folks in LA decided a fiream might be a good thing to have during a riot, but were forced to wait until after the riot to get one. (Of course, a counter-argument is that a riot is a terrible time to put more firearms on the street)