The pretty clear motivation for this is recent negative (but factually true) news about Tesla, and Musk's desire to either end negative news about his company,

The pretty clear motivation for this is recent negative (but factually true) news about Tesla, and Musk's desire to either end negative news about his company, or else get people not to trust such news. An echo chamber may be exactly what he wants. And, well, there's precedent for this strategy working to an extent.