Yes i believe our androgen is up-regulated not down-regulated.
But keep in mind AR up-regulation is different to AR density, so your theory still makes sense, because the tribulus would increase the receptor density and then the receptor could function better on lower levels of DHT. Because our DHT level is normal but it is the receptor that is up-regulated, so we either have to down-regluate the receptor to come inline with the normal DHT level or increase each receptor density so they work with the normal DHT level.
Our receptor is down-regulated while on finasteride as per this study:
But it becomes up-regulated 2 fold when we cease finasteride as per this study: