That's the idea, yes. Many of the standard Unix tools only have machine-readable output in the first place, so the effects should be minor. Mainly, anything to do with sort order, currency formatting, human-readable number formatting, date and time formats, measurements etc. is sensitive to locale settings, but many scripts don't touch these things much.
Globally clobbering the user's locale is not such a great idea, actually, so it might be better if you use LC_ALL=C only for those commands which actually require it (so
grep "$regex" "$file" | LC_ALL=C sort | uniq >file for example). That way, they still see output in their own language if there is an error message from
grep, for instance (provided of course that their copy of
grep actually has a localized message catalog).
Google a bit for
i18n if you need more information about internationalization and localization.