Yes, SFIC bases do fall into the "soap" category (that means I can even sell their MP soap in Florida if I wanted to!). For that base you would not technically have to list the ingredients as long as you just call it "soap". However, it is best/smart to list all of the ingredients on the label. For example, for the SFIC clear base and lets say lavender eo, lavender buds and purple ultramarine you would say
Ingredients: Glycerin Soap Base (Coconut Oil, Palm Oil, Safflower Oil, Glycerin, Aqua/Water/Eau, Sodium Hydroxide, Sorbitol, Sorbitan oleate, Oat Protein), Lavender Essential Oil, Lavender Buds, Ultramarine Purple
With a base from Michaels since its detergent based, you need to make sure to follow cosmetic labeling laws and follow your states laws for if you need to register ect. It will be an involved process.
I would honestly just order an SFIC soap base to make it easier for you. Then you can list is as a true soap and don't need to label it as a cosmetic.
ETA: just becasue you've seen someone not label things locally doesn't make it right. Here in Florida, home cosmetic makers are not allowed to sell their product. You have to have a commercial building and also register with the state/pay ungodly fees. However, I've seen many people who sell lotions, creams, salves, shaving soap, and soaps labeled like cosmetics. They aren't allowed to do it but it doesn't stop them.