I don't get it, did Buffett ever disclose why HE didn't authorize a buyback in 2008 and buy brk with both hands?

I suspect it’s because he had an ingrained prejudice against it which he had to work to overcome. I recall an interview in the long ago where he said he didn’t want to “buy shares from his shareholders” because he felt that he would be taking advantage of them (by buying shares he knew were underpriced.)

So while he could rationalize other corporations doing it - because he wasn’t involved - he didn’t want to do it himself and potentially fracture the relationship he carefully built over the years with his “other owners.”

I also suspect that after watching the price slump in 2008 and barely return after three years - through no fault of Berkshire - he finally overcame his own objection and set about doing some buybacks: timidly at first in 2011, then with greater enthusiasm as the teens rolled along until there was a directive agreed by the board in 2018 to pursue it as a strategy if/when the price made sense.

Just reading tea leaves, obviously. He hasn’t called me to explain his thinking in just months now.