I did check with R&D and it appears this is all expected behavior.
Officially we don’t support the legacy SNX portal any longer, thus why the updated SNX client is not placed there.
You can copy it to the correct location as you did and it should still work.
Further, using the legacy SNX portal appears to be the only way you can launch SNX via the CLI.
(As a parenthetical, SMB appliances use the legacy SNX portal only, which means launching SNX via CLI against an SMB gateway should work)
If Mobile Access Blade is used instead of the legacy SNX portal, then SNX must be launched from there.
Launching SNX via CLI is not supported in this case.