The owner of Just Thrive got back to me. We are good to go forward with it for your child. This was what she wrote:
“It’s perfectly fine to give Just Thrive to a 2 year old. The “ages 3 and up” was put there for chocking purposes.
The member can open the capsules and mix the contents of the capsule with food for her child. They can start out with a half of a capsule and then gradually go up to a full capsule. A child’s adult like microbiome is fully developed by about the age of 2 ½ so a full capsule is perfectly fine.”