TL;DR

Lawsuit in Maryland is arguing that firearms, by physical presence alone, constitute a form of intimidation, and so may violate the First Amendment in those spaces which serve a 1A purpose (museums as the main example here). Thus, exclusion of firearms from public spaces that serve a 1A purpose are legitimate, and the Supreme Court affirmed the 'sensitive places' laws (museums, courthouses, legislative assemblies, etc.) that this argument is trying to extend further.

RT: https://nicecrew.digital/objects/c3daa494-3d52-418a-8565-e902a2c510f3