I agree. I prefer this version of the saying, which is, "The blood of the covenant is thicker than the water of the womb." Sometime after I wrote my Of Blood and Water https://medium.com/know-thyself-heal-thyself/of-blood-and-water-c3f8645c856f subtitled "Tanka of ‘truth’ plus a discussion of the real meaning and origin of the phrase," additional research revealed that the version I like was probably invented by someone, i.e., was never actually spoken, but I still prefer it.