Hi Fajar,
A short contribution from my perspective.

"Responding to the client" is an constitutional accountability.

"Responding to the client by 24/7 " sounds unconstitutional, as it defines the way the accountability has to be enacted. => NVGO

I join Margaux comment. A way to precise the 24/7 availibility needed is to adopt a policy.

Impacts on the employement law contracts are not due to Holacracy, just to the real life and the 24/7 availability demand. Holacracy space is just about organizing the work. Law contract topics are part of the "association" space :  the relationship beetwen the company and the employees. It's a kind of "ressource individual agreement"

Hope that helps.