you have highlighted the confusion caused by white balance

IF white balance is set to 3000k, then 3000k IS white

there is white all along the BBL line, at all color temperatures.

but usually people compare color temperatures, using daylight white balance (5600k), and that makes 3000k look much warmer.

and as you pointed out, Tint is separate from Color Temperature. IF the tint is not above the BBL, it wont be green/yellow, but the 219c lands (slightly) above the BBL (and benefits from Lee minus green filters):

image by maukka:

maybe someone can find a tint plot like the one above, for the 3000k 219b