I went over Georges buil log again...i dint realize hes using all 1/2" tubing. I thought 3/4", for some reason, silly me.
I too have had decent sucess bending 1/2" tubing in a 1/2" conduit bender. I think i was using 4130 .035 at the time, but it was a while ago.
You should be good with 6061 alum .049 . His bends are gentle and i dont think there will be too much problem, especially working on a horizontal table. If buckling is a problem, could try sand fill.
Can you give me URL for Dr Zimmerlys build. Love to see it.