I can’t believe you noticed that in the rulebook!!
That is indeed true, the spec rules for legal bars in the USAWA state they must be a minimum diameter of 28 mm. That is in print in the rulebook.
When the rulebook was re-written in 2009, I went through these bar rules and thought I had stopped this madness. Before this time, the rules on bars for the USAWA must have been some IWF specs from the 50’s, because NO BAR now would have fell within “being legal” in the USAWA rulebook. I thought I made the bar rules “very liberal” with specifications so practically every bar would be legal, but obviously forgot about bars under 28mm. My Okie dl bars are 27mm, as well as many other types of deadlift bars. These smaller diameter bars have been used for years in the USAWA.
But rules should be followed, or the rules need changed. I will add this to the proposed rule changes for this year. Al