As a native Texan with a love of language and linguistics, I'm really enjoying all the comments in response to your question. Just so you know, there are lots of search results for that phrase outside of that article, including one as far away as Australia:

2007 financial outlook - "The Krispy Creme (KKD) Donut Boat Don't Float" https://247wallst.com/investing/2007/06/04/the_krispy_crem/

Picture of a boat that actually doesn't float: https://www.deviantart.com/theuniphotoghrpher/art/This-Boat-...

Houseboat for rent: https://www.travelocity.com/Hartwell-Hotels-This-Boat-Dont-F...

Church sermon title: https://journeyorl.podbean.com/e/when-your-boat-dont-float/

Poem title: https://inprinthouston.org/event/first-fridays-presents-rebe...

2002 article about a Ford/Mercury car: https://www.deseret.com/2002/6/11/19659250/marauder-muscle-c...

Fishing forum: https://www.fishexplorer.com/co/fxrforum.asp?action=det&pid=...

Boating forum: https://forums.sailboatowners.com/threads/new-to-the-forum.1...

Australian website asking "What happens if your boat don’t float?" https://www.aussiemob.com/beer-can-regatta/