Pitting arrogant, ill-mannered and intellectually dishonest posters

I believe that is the rule. Look at this thread:

Granted, the modnote was eventually rescinded because it was determined the rule wasn’t violated. But the rule exists and has been enforced before.

ETA: To clarify, here is where selective quoting is disallowed:

Specifically:

Do not modify another poster’s words inside the quote box. For SDMB posters, the quote must be accurate, whether displayed using [QUOTE] tags or ordinary quotation marks. Normal editorial rules apply: that is, you may indicate omitted portions of a quote by the use of ellipses “…” or devices such as [snip]. You may add text to clarify a word using square brackets (e.g., “her [the sister’s] friend”), but you may not add editorial comments or edit a quote so as to change the substantive meaning; nor may you substitute text such as “some blather” or “more nonsense” inside the [QUOTE] tags or quotation marks.

The part I bolded says you can’t “edit a quote so as to change its substantive meaning”. Removing content is a form of editing, and if you remove enough that the quote implies something the author didn’t mean, you’ve violated the rule.