> да и на официальном сайте сказано , что это не юникс.

Потому что только за право писать "UNIX" надо отвалить пару десятков тысяч ;)
https://www.opengroup.org/openbrand/Brandfees.htm
> Тable 2: Fees for UNIX Trademark
> Annual Shipments (Units) Annual Fee (US$)
> Up to 1,000 _________ $25,000
> 1,000 to 30,000 _____  $50,000
> more than 30,000 ____ $110,000

А так -- никто не считал, что "FreeBSD is not Unix!" (и в погоне за "лишь бы не как в ненавистном старперском юниксе!" пока еще не начали делать "как в венде, только нахаляву!" ))

/usr/share/misc/bsd-family-tree

The UNIX system family tree: Research and BSD
---------------------------------------------
First Edition (V1)
     |
Second Edition (V2)
     |
Third Edition (V3)
     |
Fourth Edition (V4)
     |
Fifth Edition (V5)
     |
Sixth Edition (V6) -----*
       \                |
        \               |
         \              |
Seventh Edition (V7)    |
            \           |
             \        1BSD
             32V        |
               \      2BSD---------------*
                \    /                   |
                 \  /                    |
                  \/                     |
                 3BSD                    |
                  |                      |
               4.0BSD                2.79BSD
                  |                      |
               4.1BSD --------------> 2.8BSD
<<<<<<<<<>>>>>>>>>>>>>>>>>
 *---------- 4.3BSD NET/2 -------------------+-------------*
   |                    |                      |             |
386BSD 0.0              |                      |           BSD/386 ALPHA
   |                    |                      |             |
386BSD 0.1 ------------>+                      |           BSD/386 0.3.[13]
   |     \              |                  4.4BSD Alpha      |
   |     386BSD 1.0     |                      |           BSD/386 0.9.[34]
   |                    |                  4.4BSD            |
   |                    |                    / |             |
   |                    |   4.4BSD-Encumbered  |             |
   |                -NetBSD 0.8                |           BSD/386 1.0
   |               /    |                      |             |
FreeBSD 1.0 <-----'  NetBSD 0.9                |           BSD/386 1.1