in a portfolio of US Treasuries, corporate bonds and corporate equities, presumably he is doing so to makie money.  Accepting your numbers, the interest rates are higher here, so for the fixed income portion of the portfolio he is getting a better return than elsewhere.  He obviously knows that future currency movements can help or hurt him, so he likely thinks that it's unlikely the dollar will devaluate more than 1% ish--if it does he loses the extra 1% of interest rate, and he may think the currency will appreciate, giving him a higher gain.  He likely also believe the US stock markets are undervalued, as I do, and sees that as a nice opportunity.

I would agree with that view on US equities.  I would also agree with the view on the dollar in the medium term--3 to 5 years.  I don't know what will happen in the next several years.  But I wouldn't be surprised if that is a real winning investment strategy over the next five years.