You are quoting an older draft.  The rules applied to 'master'
is actually a bit more lenient:

 - Unless otherwise specified, indent with SP that could be
   replaced with HT are not "bad".  But SP before HT in the
   indent is "bad", and trailing whitespaces are "bad".

 - For C source files, initial indent by SP that can be replaced
   with HT is also "bad".

 - Test scripts in t/ and test vectors in its subdirectories can
   contain anything, so we make it unrestricted for now.

So your particular "indent without HT" is generally accepted,
and considered a violation only in C sources.

I see what you mean by "excempt from all rules" and it is
certainly a valid approach, but I at the same time think minimal
whitespace policy should be there, and flagging trailing spaces
and SP before HT is a good idea.
-

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