I believe the gist of Bryan's argument is that the US government will monetize the debt by printing money. Dollars will be devalued because there are so many of them and that will result in higher inflation that we've experienced over the last 15-20 years. Indeed, 30 years ago inflation was MUCH higher and it made sense to load up with debt because you could borrow valuable dollars right now and pay them back with less valuable future dollars later.
Of course that works only with fixed rate debt, such as 30 year fixed rate mortgages. It doesn't work with any sort of adjustable rate debt, such as any sort of ARMs, balloon loans, or credit cards. Those debts will have their interest rates raised by the lenders if inflation kicks up.
Not sure how that wandered off into a rant against the 50% rule. All evidence has pointed to that being a pretty hard and fast rule of thumb that one ignores at their peril.
OTOH, I think there is an underlying idea that owning a rental that currently has negative cash flow when the 50% rule is properly considered may be acceptable. I agree with that idea. If inflation kicks up, then rents and expenses should rise along with inflation. If your property is leveraged with 30 year, fixed rate debt, and we do have a long stretch of inflation, then such a cash flow negative property will turn into a cash flow positive property. Inflation was between 6% and 10% between about 1973 and 1983. That means prices doubled, roughtly, over that span. So, a property that currently rents for $1000 and has a P&I of $600 might be cash flow negative right now, but if the rent rises to $2000 while the P&I stays at $600, this property becomes nicely cash flow positive.
Of course, there are no guarantees inflation will rise, which is why many investors want at least a little cash flow right now.
There's a good chance, in my opinion, that just the reverse could happen. We could have an ugly round of deflation. If that $1000 rent turns into $500, the investor is in a VERY bad position. That's exactly what's happened in Japan, though perhaps not quite that bad.
And, its not easy to get fixed rate, 30 year financing on anything but a few small properties. You're not going to get a 30 year fixed rate loan on a 100, 10, or even five unit apartment building. Those are 3-5 year fixed rates with either adjustments or balloons. That tells you lenders think rates are going up in the future.