If the NG (or ideally another federal LE agency) demonstrably reduces crime in DC, without engaging in particularly political actions, will raise some interesting questions about why things have been so bad for for long.
Aside from street protests and rallies (which NG should scrupulously facilitate for 1A reasons; DC itself has been fairly bad about this in the past, too), I don't think most local policing is highly political. Yes, DC residents are losing some democratic control over their local policing, which is bad, but DC has also done a bad job with local policing for a long time.
(I'm broadly in favor of shrinking DC to the federal areas themselves; the parts where people live generally should be returned to the States.)
Aside from street protests and rallies (which NG should scrupulously facilitate for 1A reasons; DC itself has been fairly bad about this in the past, too), I don't think most local policing is highly political. Yes, DC residents are losing some democratic control over their local policing, which is bad, but DC has also done a bad job with local policing for a long time.
(I'm broadly in favor of shrinking DC to the federal areas themselves; the parts where people live generally should be returned to the States.)