Not sure about the PI-reference in that context, but the rest IMO looks good.
How about this:
-Tabs are 8 characters, and thus indentations are also 8 characters.
-There are heretic movements that try to make indentations 4 (or even 2!)
-characters deep, and that is akin to trying to define the value of PI to
-be 3.
+Tabs are used for logical indentation, e.g., code is indented with
+a number of tabs equal to its nesting level. From there on,
+use space characters for decorative indentation. This method
+is agnostic to the editor's tab-expansion settings.
+That said, expanding tabs to a small number of spaces (4, or even 2!) encourages
+excessive nesting and resulting over-complexity; that is akin to trying to define
+the value of PI to be 3. Therefore, tabs are always assumed to be 8 characters-wide.