You're conflating two layers of gwt settings.
First question is: Does parameter affect page content? If no, then you tell them to ignore the parameter and take no further action.
All further complications, such as no-indexing any page that contains a given parameter at all, only kick in when you get to the second case: a parameter that does affect page content. You've already said it doesn't.
link to page.php?a=1&b=2&c=3
= exactly the same as link to page.php?a=1&b=2
= page.php?a=1&b=2 is removed from index
:: noting with interest that g### thinks I have a parameter called "newwindow" ... meaning that they've taken some linking site's "open in new window" code and applied it to a static html page, failing to notice that it's the other site's parameter, not mine ::