The exemption is just silly, really.
First, HB 5091(E) seems like it would offer an affirmative defense to brandishing even if the firearm was displayed with the obvious intent to threaten another, simply because the firearm remained holstered or supported by its sling while the threat was made.
Second, why on earth exempt certain modes of lawful carry and not others? Why should in-hand carry, sling-less carry, waistband carry (sans holster), retention clip carry, or any other form of legal carry not be deserving of an exemption enshrined in law?
It may be true that there is no shortage of law-abiding citizens who have been harassed for open carry under the current law, but you only want to exempt holster or sling carry, why? The proposed exemption will solve nothing, you'll soon have an equally long list, perhaps even longer, of innocent citizens charged with brandishing simply because their otherwise peaceable carry method didn't involve a holster or sling. Problem not solved!
Where this legislation goes horribly wrong is that the exemption focuses on the 'manner' of carry and not on the 'behavior' of the citizen carrying!
If you want to have a list of exemptions, make peaceable carry itself one of the exemptions, not particular carry methods for god's sake.
Since we are talking about a legislative definition of brandishing and the term hadn't been defined before by the legislature, why not start with a clean chalkboard and drop the term 'display' altogether. That is the weasel word that allows law enforcement and prosecutors to unfairly focus on the sight of the firearm, instead of the behavior of the carrier.
Define brandishing as "Pointing or waving about in a threatening manner." and be done with it.