Its not terrible advice just not something that hits home with me.
I view Tips, Reits, and Commodities as more of market timing options. Not market timing as in daily trading but as in they are good investments for periods of time in each decade and not so good in longer periods of time. I do not typically put enough effort into my investment mix to worry about timing those things so I guess if I was inclined to want to own them that I could via a target date fund. Many of those funds carry decent %s in those areas.