Why did Milton Friedman prefer (technical) private monopolies over public monopolies?

"When technical conditions make a monopoly the natural outcome of competitive market forces, there are only three alternatives that seem available: private monopoly, public monopoly, or public regulation. All three are bad so we must choose among evils. ... I reluctantly conclude that, if tolerable, private monopoly may be the least of the evils." [1]

I am going to guess this is a firmly heterodox view that might be caused by his public choice theory and political philosophy. What premises would it take for his view to be accurate, and what premises would it take for his view to inaccurate?