I take issue with these two things.
Juggs achieve this stat with just standard gearing, whereas an example of an Assassin tank, they need to regularly use an ability called Dark Ward which costs force to keep their shield chance about 50%. I have a sin tank, even with the campaign set bonus my Shield chance is as 40% without DW while Defense is 35 and absorption is 60. A sin that has 35/60/60 is pretty solid from my experience, and the Juggernauts when Min/max can achieve this same stat base.
My shadow is sitting at 28/ 50/ 60 full campaign gear (with rakata fort stim) with the correct mods, enhancements (save for one, need to replace a Vigilant Enhancement with a Bulwark) and augmented (9 defense, 4 shield 1 absorb) and mathematically having 28/ 70 (with KW)/ 60 is better than being 35/60/60, especially with the DR on Defense being higher than the DR on Shield
My sin's HP min-maxed is 24k. with the stim + trooper buff when specced into Mental Fortitude
/ Shroud of Darkness
and 23.6k when I replace those three points with Expertise
/ Electric Execution