AIUI...
It simply means that the LEA (SD) in that county is not going out of their way to infringe upon the 2A rights of the people.
It does NOT mean they are not going to arrest an individual who goes out of their way to be confrontational... or violate other laws.
Nor does it mean that another LEA with jurisdictional authority in said county... won’t enforce the laws as written.
Folks in those counties must exercise ALL due care and caution, take NO unnecessary risks, and realize that a courtesy it’s being offered to those who do not press the issue. That courtesy being... “We are not going to actively pursue cases against everyone who otherwise behaves themselves.” But if someone forces their hand... they can expect the lawful charges to be added to their case as the SA deems necessary.
IANAL
Nailed it!
tl;dr: Civil right virtue signaling in MD.