Tires: Damaged tire

Question
Hi Barry,

I own a 2010 Honda Accord EXL with 32m miles on it.  I do all maintenance on timely basis including tire rotation of Michelin tires about every 5m miles.  Recently I noticed drivers side rear tire losing air.  Took it to a reputable dealer who has repaired punctures with boots for my family for years with good success.  They pulled and checked problem tire and found a rather large machine screw that had penetrated at an angle the tread area and damaged interior to point where they said for safety reasons they would not repair...said the damage was such that tire would continue to tear in that area and good possibility it it would ultimately fail.  I agreed with their assessment...did not want to knowingly put my family or other passengers at risk for the cost of a new tire.  I purchased and installed a comparable new Michelin tire.  The owner of the shop said I should leave the new tire in that position on the rear and not rotate it to front since it would be a problem in the case of a sudden stop with one worn tire and one new tire on the front.  
My questions are, should I just go ahead and buy a new tire for right rear giving me two new and two with 32m miles and rotate them as usual keeping old on same axle and new on same axle or just drive them in same position until I need to replace the 3 old tires.  I have been driving autos for 60 years and this is the first time I have ever had to replace just one tire because of damage beyond repair.
Thanks in advance for your assistance.
Ernest

Answer
Ernest,

The problem with having odd tires on a vehicle is that during an emergency maneuver, vehicles tend to pivot around the odd tire - and the more different that tire is, the stronger that tendency.

What would be "more different"?  In order from more to less:  Brand, size, speed rating, model, different wear, age.

So in that respect, you are on the low end of things.

That should be enough for you to be able to make a decision.