One basic point that bears mentioning -- it is governmental entities (states, counties, municipalities) that cannot infringe on free speech and other constitutional rights. Stated differently, the constitution protects citizens from government action, not from private action. Civil rights laws (statutes) provide protections that are enforceable against private actors in certain contexts (housing and related services, employment, access to facilities, education, etc). But again, private entities like an HOA do not violate the constitution when they regulate speech. This is a distinction that many people don't appreciate when they cite the constitution as a prohibiting regulation of political or other speech by an HOA where they live, or by a private company that may be their employer.

In the absence of the Maryland statute that prohibits HOAs from restricting election signs in the period 30 days before and 7 days after an election, OPA could (particularly in light of the sign restriction in the DRs) ban election signs outright, and there would be no free speech/constitutional violation there, because the OPA is not the government.