According to a new article in a Great Falls paper, he is. Tester has been slashing recommended wilderness acreage when mountain bikers complain about a specific trail. In fact, this article points out three instances in which Tester did just that:
For example, in far southwest Montana’s Sapphire Mountains, the bill moved Trail 313 out of proposed Sapphires wilderness by adjusting the boundary. It was previously running in and out of proposed wilderness.