I agree with what Ms.Sarah D has stated. In India, where English is second or third language to many, I have heard people saying electric city for electricity , or petrolmax for petromax. The distortion is unintentional
Your coworker might have come across several words like disagree, disharmony, dishonest, disengage, disinfect, disable etc where the word 'dis' has been added to some words to form words describing opposite states, qualities or process. Hence,he added 'dis' to the word 'activate' to describe a process opposite to activate.