It is up to the owner of the range whether to allow supressors (or anything else). The range I use permits their use. The owner says it drives his insurance company crazy but there is no restriction against supressors in his policy and since it is legal for game hunting in Texas for over a year now, there is no reason to disallow them on his range.
Curious - why would the insurance company care about suppressors?
What added risk exposure would there be for the underwriter?
WHY?? It makes no sense. If they had any opinion at all I'd think they'd prefer them so they don't get sued for hearing loss (though I'm sure you have to sign a waiver).