Maybe he does, but his post does not show it. Best reading is that he does it because he is interested in return-on-investment money. In which case his title should be "bonds are not useful for high return-on-investment". But no, he chose "Why in the world would you own bonds?". And then he doesn't even really answer that question, he just goes on about his investment strategies. His result: Don't own bonds.
This pretty much explains his "…The economics of investing in bonds (and most financial assets) has become stupid" paragraph.

I already answered why bonds are still valid to be owned by institutions with lots of money and also why big banks still buy them (happily, I should add).

> The world is a) substantially overweighted in bonds (and other financial assets, especially US bonds) at the same time that b) governments (especially the US) are producing enormous amounts more debt and bonds and other debt assets

Yes and no. Why are there so many bonds? Well, lots of countries have policies to not issue money directly to the finance ministry which then gives the money to whatever the government wants to fund, but instead for every spending of the government issue bonds that are sold to banks and put that money on the finance ministries balance sheet. It's an entirely political concept, but it's reality. As such, bonds and state debt are just the money handed out by the state. If they would not hold debt and/or issue bonds, there would be no money for anybody. Period.

>…If bond prices fall significantly that will produce significant losses for holders of them, which could encourage more selling

This leaves out the political dimensions in its entirety. Bond prices will not fall significantly UNLESS the state's resources (technology, work-force, ...) also drop significantly. If that is not the case, the state can just uphold the bond's values.

> …Imagine what would happen if, for any or all of these reasons, the holders of these debt assets wanted to sell them. There is now over $75 trillion of US debt assets of varying maturities.

This is just wrong. I already explained why, in brief, above. I won't shed anymore words on this, except that it is fear-mongering.

> …History and logic show that central banks, when faced with the supply/demand imbalance situation that would lead interest rates to rise to more than is desirable in light of economic circumstances, will print the money to buy bonds and create “yield curve controls” to put a cap on bond yields and will devalue cash. That makes cash terrible to own and great to borrow.

There are more sides to that coin. This is often used to create fear for inflation. Because history has also shown that unless there is hyper-inflation people always love to own cash, regardless of the economic circumstances. And better borrowing conditions should enable economic growth, and over-borrowing should be kept in check anyways (re: financial crisis 2008) so there is no real issue here. And as explained above, unless the resources of a state drop significantly, there is no trigger for hyper-inflation.

All in all, he is just arguing from an invester's perspective, but even then not a very holistic approach.