I disagree. The personnel at HTS is virtually the same as the "external" manager, Atlantic Capital Management, LLC, based in Winston-Salem. ACM is a partnership established to implement their investment strategy of buying mortgage securities and using repos as leverage to expand the market value (and returns) by about 7 times. At first, in order to attract outside investors, they had to establish a trust to hold the assets. Then, in order to expand even further, they established HTS. Public information isn't available about ACM, LLC, but when you look at the top shareholders of HTS, you'll see the names of every partner of ACM.
My opinion as to why they do not want to buy back stock is: It would shrink the size of the investment portfolio. The smaller the portfolio, the lower the returns. I realize that's simplistic reasoning, but it's what I believe.
The main point is that there is little or no conflict of interest, IMO, between ACM and HTS. The partners at ACM are major shareholders in, and make their money from, HTS.