Is a change in colorspace needed when comparing colors only evaluated by the computer?
Delta E color difference formula is based on CIELAB color space and human perception. To convert from RGB to CIELAB space, you would need a base whitepoint (standard illuminant) which in this situation you do not have and need. 

Your assumption is correct. You do not specifically need to have a color difference similar to human perception. Additionally color distance metric should be based on your needs (you can use weighting depending on your needs).