Interestingly, the Leedsichthys in the dev kit had a knock out animation with a knocked out eating animation. There was also a successful tame animation and a failed tame animation. This strongly implies that the Leedsichthys was tameable at first and explains why when forcetamed, it can be ridden.
It says these are “non-Tamable,” but they have a knockout animation, knockout feeding animation, failed tame wake up animation, and a succeeded tame animation. Make green under this if u found this true.