Which is the role of any nearby citizen.
The praetor using the lictor weren't just any nearby citizen. Ignoring the use of the lictor and focusing on the lictor as though independent just doesn't mean they weren't fulfilling a law enforcement role, which included legitimized violence by state authority.
The point that the use of 'cop' was too narrow or obscure to fit a meme is certainly not an invitation to unnecessarily and pedantically widen the definition as though to clarify a pretty basic point, nor to perpetuate useless argument.