I haven't re-read all the old posts in this thread, so I may have mis-understood, but :
I'm assuming there, you were referring to what is known as value-investing. Where one is particularly only interested in taking LONG sided ownership of securities when they become undervalued (often during drawdowns).
As for their shorting practices, they never short on margin, but they do short PUTs and CALLs. One prefers on individual stocks, and the other prefers LEAPs on indexes.
That said, Buffett has stated that he would like to purchase 5-year LEAP PUTs on Bitcoin, but that he couldn't find anyone willing to give him that kind of size and duration.
He believes he knows BTC very well, however, he doesn't seem to understand Ethereum. Well... you can't expect a boomer going on to his 100s soon, to really understand coding and DeFi, can you? While it's possible he may understand part of the gist of smart-contracts, he has never so much as mentioned Ethereum that I recall or anything else in regard to the world's EVM. This leads me back to the same conclusion, he doesn't understand Ethereum.
Some investors manage to do ok when they have the financial statements of public companies in front of them and a staff to help them do intverviews with the CEO and other benefits. But put them out of their environment from the last 80 years and nothing makes sense to them anymore.