The problem with defining "The" brand color as a device dependant CMYK color is, its appearance would change depending on the document’s CMYK profile (the print condition).
So if you start with a source CMYK color like 60|30|50|0, you can see the value’s appearance changes depending on the assigned CMYK output profile.
Here’s Coated FOGRA27, US Sheetfed Coated, and US Newsprint SNAP. Which one would represent the brand’s intended appearance? In these cases you would get different conversions back to RGB depending on the source CMYK profile assignment.



The Pantone solid ink library swatches are defined as Lab, so the color is not affected by the document profiles. The Lab swatch is displayed directly in the system’s monitor profile—the accuracy of the preview only depends on the accuracy of the monitor profile.
You could also reference a printed PANTONE solid ink swatch as the brand source. Just keep in mind not all Pantone solid ink colors are in the CMYK or RGB gamuts.