You are very intuitive. You make a great point that the scar that covers the annular tear is not as strong as the original collagen tissue that had torn. You are also correct that the pressure drop in the nucleus reduces the stress on the torn annulus.
Interesting that there are no case reports of recurrent thoracic disc herniations that I know of in the literature. There would be no recurrent hernations after surgery as surgery is designed to remove the herniation and fuse the level. The recurrence rate for lumbar disc hernations in an active population is about 10%.
A sequestered fragment (one not attached to the tear of the disc) can migrate but normally will migrate out of the canal and usually not cause further problems.
The chance of another disc herniation is limited. If you have Scheuermann’s disease (see website), you do have a higher chance of a herniation at another site, but still that chance is small. The positions of yoga you have sent by itself should not cause a herniation. However, if you already had a complete tear and load the disc in that manner, the herniation could occur.
There are some spine surgeons that think “If I have a hammer, the world looks like a nail” and everything is a surgical answer. I would like to think these individuals are rare. The surgeon should be the best person to determine if surgery is right for you. Many spine surgeons are also great diagnosticians and will discuss with you your options and should not push surgery unless it really is indicated or you are well informed of your options.