When I say "fluoride works topically, not when ingested", I mean there's no benefit to teeth from swallowing fluoride, the only benefit to teeth is from it touching teeth directly. That link doesn't say that there's a tooth health benefit from swallowing fluoride.

Both toothpaste and water supply cause some fluoride to touch the teeth (topical) and some fluoride to be swallowed (ingestion). However, toothpaste has a higher ratio of topical application to swallowing, vs water supply which has a lower ratio of topical application to swallowing. That's why I said toothpaste is focused on topical application and water supply is focused on ingestion.