According to the blog, the tensile strength of ligaments and tendons varies between 50 and 150 MPa, however, they used 50 MPa in the account. Using the low-end isn't safe as they are below average. Average is the safest to use, so 100 MPa or 1019.72 kg/cm^2.
(12.9947002361 x 1019.72) + 766.060761049 = 14,017.0164858 kg-force, Class 25