A distinction needs to be made between calibration and profiling. Apple displays have no accessible hardware level LUTs. Generating a profile for a display is similar to a printing device. If it's close, it may get it a bit closer. I would check the profile assigned to it in system preferences. Neither of us can really see what the OP is looking at here, but if it's going truly yellow using the base profile within under a year of use, that is a hardware problem. Defining an altered profile through your suggested method isn't lossless, and it doesn't counter display aging.
Edit: They shouldn't ask if you calibrated it as Apple doesn't even suggest any means of proper calibration.
Next thing is all of these displays do shift over time. If it's excessive and the display is newer, which it is here, you probably have a case. All of them age over time. Some go a bit faster than others, but I've seen plenty of this before. Typically you should be able to expect two years of heavy use out of a display before you experience any real issues with this kind of stuff. Overall there are a lot of things I liked about the 24" more than the current ones. Tell me, did you buy it from Apple? I haven't seen the 24s listed refurb in a very long time.