You are 100% correct. The sentence should read, "it is essential to the police to be in good standing with the community." If a significant percentage of the public, or even a highly motivated small minority is actively opposing the police then their job is impossible to perform.
Common sense and simple numbers show this to be true, and it is amply confirmed by historical experience here and in other countries. Does anyone really think even 100 police officers wearing whatever body armor they have and carrying carbines could effectively hold off any significant number of irate civilians? We all just saw what really happens long before any shots are even fired when perhaps 400 or so armed civilians showed up in Nevada. And even though that situation ended peacefully the overall dispute was apparently sufficient to trigger the murder of several police officers subsequently by a couple of deranged anti-police individuals.
A quick look at any country suffering serious civil strife shows that the police are very quickly rendered ineffective, regardless of whether they are heavily armed or not.
Police depend on community support and cooperation, and must have that to function.
as long as the cops are not in good standing with thugs