Bonds will give you poor (probably negative) real returns, but if you're 10-20 years away from dying you're more concerned with wealth preservation than growing your wealth.

People have forgotten this but equities are an infinite duration asset that are prone to periodic, significant, often violent crashes.

(Edit: often at a time when everyone is absolutely convinced they're the best asset class...)

You can keep some equity exposure but you don't want 1929 or 2008 to happen the day after you retire when you might live for another 30 years