Nitrous oxide acts on GABA-A and potentially even directly on benzodiazepine binding sites from what I recall.
This means that yes, nitrous oxide has the potential to prolong benzo withdrawal as it may slow the upregulation of GABA-A (ie, the return to homeostasis).
That said it is pretty short acting, but prolonged and frequent use might slow down the healing process. I have used it during benzo withdrawal and it provides very substantial relief from benzo withdrawal anxiety. At the same time it does exacerbate the psychosis of benzo withdrawal due to its NMDA blockade, but due to its GABAergic and opioidergic effects, it is a very comfortable psychosis.
Overall though it's use isn't advisable. You'll feel better instantly but inevitably it will wear off, and you'll still be in benzo withdrawal yet even more dissociated due to the residual effects of the nitrous oxide.
Personally I have found that nitrous oxide is the only dissociative that really helps benzo withdrawal, but this is almost certainly due its strong GABAergic properties. Other dissociatives make benzo withdrawal more uncomfortable in my experience, as they increase dissociation (which itself is a benzo withdrawal symptom).
