He used a margin loan for part of it (you can think of this as extracting money from unrealized gains, but it's kind of different), liquidated shares for part o

He used a margin loan for part of it (you can think of this as extracting money from unrealized gains, but it's kind of different), liquidated shares for part of it (realizing a gain in the process), and will pay interest on that margin loan (realizing a gain for each payment) for the duration of the loan. If he wants to pay off the loan, he will have to realize a gain. The margin loan is effectively tax deferral, not tax elimination.