I’ve seen 5yo as the age of the youngest in other MSM sources as well.This article gives the four children's ages as:
20, 18, 15 and 5 years old,
https://www.expressnews.com/news/article/suzanne-simpson-brad-san-antonio-missing-19829447.php
(moo i wouldn't describe a 5 year old as a "toddler" but instead a " young child" or "preschooler". But she's going through a lot certainly so very understandable. Ps assuming the article is correct)
I think a lot of people have a fairly broad interpretation for toddler, but I’d venture more to say, in my personal experience, the youngest child, especially with a 10 year spread to the next closest sibling, is often thought of as the “baby” and younger than their chronological age for longer than other siblings.
But gosh- the thought of Suzanne’s poor kids at this time… no matter their ages… I can’t even fathom the fear and confusion they must be feeling. And her poor mother. Hard to think about their pain.