Joe Wood at Satoshi Pacioli has always struck me as guy who does a good job balancing fiat tax concerns and Bitcoin knowledge.
Herr's a few things he said in article about Bitcoin loans and taxes.
If you are using a loan to avoid long-term capital gains of 15%, but paying 13% in interest per year the short-term effects may be minimal or even negative.
If the bitcoin is held until death, heirs typically receive a step-up in cost basis, meaning the unrealized gains are erased and the heirs inherit it as if they bought at the current market price. So by borrowing against bitcoin (to access liquidity without selling), an older person can use their wealth during their lifetime while preserving the tax advantage of passing on bitcoin with a stepped-up basis.
Businesses have the unique advantage of having interest be deductible from taxable income.