Ah, I misinterpreted "this alias" in your post! So you meant (I added italicized text): "I like to define :sql as a way to launch the shell and execute a statement - so that means this built-in :sql alias should be renamed by InterSystems to something else!! or be removed."

At least aliases defined in .iris_init override any built-in aliases.

I have one older IRIS instance (unreleased v2021.1 with some Python extras) that has the following aliases built in. The :sql alias doesn't run Execute() like it seems to do on yours.

:py          Do $system.Python.Shell()
:mdx         Do $system.DeepSee.Shell()
:sql         Do $system.SQL.Shell()
:tsql        Do $system.SQL.TSQLShell()

Here's some info that was inadvertently removed from the docs, but will be returning soon:

On Unix systems, if a file named ~/.iris_init exists, it is read when a terminal session is initiated. Only lines starting with :<command> are processed. All other lines are ignored. This file accepts only :alias commands, which enables you to store favorite command abbreviations there.
Example of a ~/.iris_init file:

# Initial aliases
:alias %  zn "%SYS"
:alias load Do $System.OBJ.Load("$1",$S("$2"="":"ck",1:"$2"))
:alias ut Do ##class(%UnitTest.Manager).RunTest("$1")
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