Keep in mind how many shares he still has. From the link: "Berkshire (ticker: BRKB ) subsidiaries sold 13 million Delta (DAL) ...Berkshire now has overall ownership of 58.9 million Delta shares" "Buffett’s firm also sold 2.3 million Southwest shares (LUV) ... Berkshire now owns 51.3 million Southwest shares" So selling 2.3 million out of 53.6 million and 13 million out of 71.9 doesn't exactly imply that he thinks his position is going to 0 in bankruptcy. The LUV sale was extremely small and looks like he might have been trying to stay under some ownership limit.
It was small, but if he sold to stay under an ownership limit then wouldn't that mean he was already over said ownership limit? The fact that it was two airlines at the same time also would tend to indicate more that he was trying to reduce his exposure to the sector.
I think he’s sub 10percent now. Might be a critical number if there was some kind of bailout clause in the works.