"Don't mess with us" is the translation of the lyrics of the song playing at the end the execs are dancing to. Earlier in the video they do say they want to crush their competition and show a clip of a hand crushing a soda can.

The song is played as the outro so could be interpreted as a last word on the video as a whole. It's not exactly clear what the intention of the lyrical translation is.

The CEO also states in the video that they are no longer asking nor negotiating, but informing of the policy. Seems pretty straight forward that it is a demand and that employees' jobs are at jeopardy if they choose not to comply.