Indeed the Codex Alexandrinus shows signs of tampering but the tampering was in favor the idea of the deity of Christ over the original “he” reading.
It appears from your comment you may not have read the entirety of my post. That tampering occurred is not in dispute. What motivated it is. There have been eye witnesses to the physical document who believe the text did show the “theos” reading in faint but detectable form, but was suffering from years of poor handling, and thus was “retouched” by some anonymous person, not to show what wasn’t there, but to restore what was there. Nevertheless, the tampering suggests that Codex A cannot be used by either side as conclusive evidence, and the default must go to better text forms, not the least of which is the Byzantine, which clearly does have the “theos” reading.
As for Metzger and his ilk, they have demonstrated an unwholesome willingness to modify the Biblical text for such low reasons as appeasing the gender equity ruffians. These are not people who understand or appreciate that every word of that Bible is God-breathed. Furthermore, their “weight of the evidence” is an ideologically charged statement, and on close inspection I believe you will find their model for variant selection is seriously defective. Metzger has written that he specifically prefers readings that create conflict, because he thinks that’s more real. Seriously.
These folks have been following the German higher critics into the bowels of Hades for decades. But hey, if the NWT appeals to you, I can understand why Metzger might. Just sayin ...
Peace,
SR