I mostly agree with this, except I also think it's pretty important to have at least one other co-founder... but it's even more important for you to be able to trust and work well with those co-founder(s).
Going out and finding some random dude that you don't know or trust to be a co-founder for the sake of having a co-founder seems like a huge gamble and just a bad idea.
If you've known someone for awhile and you know they would be a great person to start a company with (and you have the emotional maturity to be abel to tell that- I mean, how many people think they are going to get married to the person they are dating, 5, 8, 12 times before they meet the person they know they are going to marry and with whome it works out?) ... if you already have a cofounder, even if you don't have an idea for a company yet... then start a company with them. Nothing wrong with that.
My point is just that if you don't have this person... don't hesitate for a second. Just go forward and get employees or go without them.
If it means you don't get YC funding because of PG's bias, then you didn't want it anyway.
Just don't hesitate to start a company without a cofounder... most successful businesses are founded by individuals.