DWC_2.7T

I had a sidewall cut on my LR tire and the tire dealer says I must replace all four because of quattro. My 2.7T manual says "All four wheels must have the same rolling radius" and "The proper function of the (quattro) system is not affected by unevenly worn tires". I see some posts here stating that a new tire must be within 4/32" wear of the others. I have about 5/32 tread left on my front and 6/32 on my rear. These are 3yr old Conti Pro Contacts.

Can any tire experts advise on whether I can replace only the damaged tire? Maybe I worry too much and should just take the Audi manual at face value and go ahead.