BA may be a very good ATF fluid for Z1 applications, but it's not Honda labeled Z1. Z1 is a proprietary Honda oem product that only Honda sells, or in this case used to sell. ATF 'for' Z1 does not make it the same as Honda labeled Z1.
As to whether BA ATF is an exact chemical match to oem Z1, without analysis is speculation. In any case I'm doubtful that it is any better than any of the other aftermarket ATF's mentioned in this thread, that now have suitable/recommended for Z1 and DW1 on the bottle and/or data sheet.
Now with Z1 superseded by DW1 all Hondas have been back spec'd to DW1. Looking back at Z1, as far as shear stability, it was really nothing special. I'd say any of the current alternative ATF's noted in this thread are better than Z1 was.