via the official Facebook page of U.S. Senator Bernie Sanders (I-VT)
The document quoted is the 1980 Libertarian Party Platform, not anything personal to David Koch or particular to his candidacy for Vice President that year. To the chagrin of some in the party, the Clark/Koch ’80 campaign actually did not openly advocating the abolition of all taxes, instead calling for substantial tax decreases. Clark’s use of the phrase “low-tax liberal” to describe himself, as well as generally downplaying or rejecting more radical libertarian planks, was one of the causes of the split that lead the Koch brothers (along with campaign manager Ed Crane) to leave the Libertarian Party shortly thereafter. Aside from funding the campaign, David did not actively campaign himself in 1980.
It’s noteworthy that Bernie Sanders would choose to bring up the radical anti-tax policies of minor parties from that era. The Liberty Union Party, which Bernie Sanders was a frequent candidate and leader of from 1971 until 1977, called for the abolition of taxation on all but the rich. One of the slogans of Bernie’s 1976 campaign for Governor of Vermont was “Vote Tax Relief.” Like David Koch and the LP, Sanders eventually parted ways with the Liberty Union Party, denouncing its ineffectiveness and internal ideological divisions.