When he said inhibiting, he probably meant inhibition of the production of DHT. Systemically, this is a huge problem because of side effects. The way to go would be to block DHT by occupying androgen receptors locally selectively, e.g. in the scalp. That way, you could keep your body's 5ar (5 alpha reductase, which produces the DHT) untouched, while still eliminiating the negative effects of DHT selectively in your scalp.
Finasteride, for example, inhibits DHT (production) by occupying 5ar, preventing T from docking to 5ar. T docked to 5ar is being converted by 5ar to DHT. The problem is that finasteride, the active ingredient of propecia, works systemically and thus also shuts down DHT production in your testicles, for example. And you dont want that.