How does he reconcile those two things?
[...] George Canning, who was briefly prime minister in the 1820s, gave a speech defending rotten boroughs. One of his points was that rotten boroughs like Old Sarum, which had two MPs and no residents, produced some of the finest parliamentarians of the late 18th and early 19th century: people like William Wilberforce and William Pitt. Canning argued that if you did away with the rotten boroughs you would lower the quality of the House of Commons. Of course, this is an exact parallel to the arguments about the reform of the House of Lords today. And in a way he had a real point: so it demonstrates why, if one is a democrat, it is important to stick to the principle of democracy. Because if you get into the functionality, if you say the principle is to get the best people or the best government, you might well end up arguing against democracy, which has to be defended as a good in itself.
(my emphasis). Democracy is good in itself - even if, nay, even though, it demonstrably produces worse outcomes than its alternatives.
So that's how. Read the whole thing at Five Books.