Err... this isa bit off subject.
But man what game you playing? Shadowtanks have the best mitigation of force/tech attacks of the three tanking classes. If you are kinetic damage, than yes the shadow is weaker. But over all because of the self healing abilities shadow has greater surviavability than jedi guardian.
Shadows actually have weaker mitigation for Force/Tech attacks than Guardians and Vanguards, assuming they aren't Internal or Elemental damage. Only then do Shadows get a leg up. I should have clarified I meant Kinetic/Energy coming from Force/Tech attacks. This means the attack can't be shielded or defended (one of the Shadow tanks strengths) but is affected by all of your damage reduction including armor (Shadow tank weakness).
There's a difference between attack type (Force, Tech, Melee, Range) and damage type (Kinetic, Energy, Internal, Elemental). The first decides how defense and shield interact (only Melee and Range are affected by these, Resistance applies to Force/Tech), the second decides how your damage reduction and armor interact (Kinetic and Energy respect all forms of damage reduction, Internal and Elemental ignore DR from armor).
Internal and Elemental will only ever come from Force and Tech attacks, but that said, the majority of Force and Tech attacks are still classified as Kinetic and Energy damage.