Like I said, not an election law lawyer, but 2 points:
1: Hatch act does apply to state employees if their agency receives any Federal money. Not sure if this applies to @SFDAOffice ; and
2: California Law (https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=GOV§ionNum=54964 …) prohibits spending public $ on campaigns.https://twitter.com/richieSF2016/status/1267626043285712898 …
By working on this issue while at work, @chesaboudin is spending his salary on campaigning for a political measure and against potential opponents.