Don't tell me, let me guess... this is this guy in Kiplinger's, Stephen Goldberg, who tends to like active funds and once harshly criticized the president and VP for not setting a good example by having enough stocks in their personal investments,
cautious to a fault, am I right? Yes, I really
did guess and I was right.
By the way he makes an error of fact at the end. Vanguard's Intermediate-Term Investment-Grade bond fund, VFICX, contrary to what he says, is
not an index fund. Vanguard's own fund screener classifies it as "active."
I would say that if you take all of the stuff people write about Total Bond you will see a range of opinions--most, of course, expressed with total certainty and confidence--that go in diametrically opposite directions.
It is a fact that the Bloomberg Barclay's US Aggregate index has this composition, or to put it another way, this is what the "investment-grade, US dollar-denominated, fixed-rate taxable bond market" invests in. Most of the dollars in that market are in government issues and very-high-credit-quality Aaa-rated bonds. That's what "the bond market" is.
Most of the dollars in "the" bond market (I'm putting it in quotes because there isn't any unified bond market comparable to the stock market) are in government bonds. Perhaps that surprises people, just as some people seem surprised most of the dollars in the US stock market are invested in large-caps. So anyone who wants to attack indexing can introduce fear by saying "most of your money is in X" and then raising doubts about X.
Another objective fact is that corporate bonds have become considerably less liquid since 2008-2009.
Here's the dichotomy. Government bonds have less credit risk, lower return, and higher liquidity; corporates have more credit risk, higher return, and lower liquidity. Thus, John C. Bogle has suggested, essentially, that the Bloomberg Barclay's index, and thus index funds that track it, have a government allocation that he thinks is higher than most investors should want, and that the normal retirement saver should take more risk in corporates in order to get a higher return. That's a reasonable viewpoint that should be measured against one's personal risk tolerance.
But at the same time, we have just seen the collapse of a (very unusual, lowest-of-the-low credit quality) junk bond fund, Third Avenue Focused Credit, due to liquidity problems in the bonds it invested in. Part of the appeal of mutual funds is that they are required to provide daily liquidity--you can redeem your fund shares for end-of-day NAV regardless of whether there is anybody out there at that exact instant in time who is interested in buying the assets in the fund. Since they provide daily liquidity, they are prohibited from investing more than 15% of their funds in "illiquid" assets. However, I guess liquidity is somewhat in the eye of the beholder, and as bond categories that were traditionally liquid became less so, both the IMF and the SEC began to be concerned about it... and in October the SEC passed new "liquidity and swing pricing" rules that allow bond funds to take actions to slow redemptions when there is a liquidity problem.
In other words, Goldberg doesn't like and raises alarms about "US government debt," which he even calls "The government-debt bugaboo." But it would be just as easy to raise alarms about liquidity problems in corporate bonds.
In reality, I don't think either of them amounts to a hill of beans in a fund like Total Bond. The world being what it is, serious problems in Treasuries certainly could happen, but would precipitate a global crisis which would unfold in unpredictable ways, and holding a corporate bond index fund wouldn't be much of a shield. And the liquidity question mostly involves junk ("high-yield") bonds, and even if it happened, in a "normal" junk bond fund would probably just be a nuisance--a short delay or an imposition of a small fee for redemption.
If you have a fear of Treasuries for whatever reason, there's not a thing wrong with Goldberg's alternative suggestions of Fidelity Total Bond (FTBFX) and Vanguard Intermediate-Term Investment Grade (VFICX) but be aware that yes, of course there darn well is some additional risk, as shown in their behavior in 2008-2009. Vanguard Total Bond Index, blue; Fidelity Total Bond, orange; Vanguard Intermediate-Term Investment Grade, green. It was only about a 10% hit when stocks were taking a 50% hit, but still. And as you see, in the time period shown, the obvious extra risk was compensated by obvious higher return. Exactly what you'd expect.
Source

Annual income twenty pounds, annual expenditure nineteen nineteen and six, result happiness; Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery.