They're probably working off of the 1970 Osmonds song, that completely flipped it: "
One bad apple don't spoil the whole bunch, dear."
You can't expect such a person to know anything about Bobby Peel's 9 Principles. [0] If anybody on this site knows a US cop that can name even a single one of them from memory, I would be very surprised, even though they form the ethical foundation for the entire profession of modern policing, along with some of Jeremy Bentham's work.
Peel organized the Metropolitan Police in 1829. Boston copied it in 1838. New York City followed suit in 1845, and Chicago in 1851. It spread fast to all northern cities (southern policing being largely based on the slave patrol instead). The "thin blue line" that seems to be endemic among professional cops in the US is a blatant violation of number 7, and severely undermines number 2.
That cultivation of an "us versus them" mentality, and the erosion of public trust and cooperation with the police, makes the force a decidedly non-modern police force--more like that military occupying force Peel wanted to avoid.
[0] https://en.wikipedia.org/wiki/Peelian_principles