Dudenals, it's an issue of what
state law allows or doesn't allow. Federal law has nothing to do with it.
Ohio weapons-law provides zero authority for the governor, county comm'rs, or mayors to suspend firearms carry-rights and rules set forth in the statute.
My take: law-abiding citizens (LACs) who choose to carry - concealed or openly - in Cleveland during the convention won't be the problem.
In Dallas, there were several openly-armed protesters exercising their 1A-rights who, amazingly, killed no one. No doubt too there were more than a few protesters carrying fully concealed. When that bad guy-wacko starting firing, a few of these same open-carry law-abiding protesters immediately surrendered their firearms to the nearest cop, for the obvious reason to avoid being mistakenly shot by all the other cops rushing around.
Assuming the exercise of first and second amendment rights will necessarily conflict only diminishes the exercise of both sets of rights, or plays one off against the other.
Suspending constitutional rights in dicey situations is never the answer; all it does is set the needed precedent to make it easier to do it again in non-dicey situations, ... or wherever President Hill-Bama deems it necessary.