Not only that they are rejecting sources like the Greek bibles and the Vulgate that are far older than their precious ‘aleppo manuscript’.
We’ve got Greek manuscripts back to the 4th century. I wonder why they are refusing to use the best textual evidence?
Because they have some quite serious doctrinal differences with the official Masoretic Text, and that causes some discomfort. The fact that most of the LXX differences are supported by both the Samaritan Pentateuch and the Dead Sea Scrolls, of course, causes even more discomfort.