If get-NaVolOption returned a single hashtable instead of an array of tables, you could use an indexer on it and that would make it a bit more friendly. Perhaps a suggestion for the next revision of the ONTAP toolkit?
The design goal was consistency between Get-NaVolOption, Get-NaAggrOption, and Get-NaOption. But Get-NaOption returns values with three fields (key, value, cluster constraint) that don't lend themselves to hashtables. However, the utility of accessing option values in a hashtable is obvious, so we'll consider that for a future release. I suspect that for compatibility the default behavior would remain, and something like a -Hashtable switch parameter would yield a single table instead. In the meantime, the suggested code for copying the values into a hashtable works well.