Vitamin K2 does help bones absorb calcium, but it will not prevent the blood calcium level from rising if you are really taking more Vitamin D than you need. This is simply wishful thinking.
A vitamin K deficiency with normal vitamin D levels would cause blood calcium levels to rise. Many people are deficient in vitamin K since it's mostly found in leafy greens and liver, no one's favourite foods. The difficulty is judging what is a normal vitamin D level by incidence of people with elevated calcium levels in the blood without having tested all of those people for vitamin K deficiency first.