Degrowth as used in the OP article is about macro level policy. For example solar panel subsidies, taxing coal and investments in public transportation.
Individual actions performed in the name of "growth mindset" (whatever that means) can like any other actions be stopped, and likely will be stopped if they cause harm to others.
In capitalism, these are entrepreneurs. In democracy, these are politicians. In autocracy, these are dictators, army generals. In theocracy, these are pharaos, etc. In nature, these are alpha wolves.
Even people proposing degrowth, if they're going to achieve their goal, will have to be power hungry, alpha wolves (no matter how they will market themselves), not that different from people I describe. And they will have to fight constantly. There is no way how to stop need for getting better, getting more, competing, winning...
No, neither is a fundamental right. Because both growth and degrowth as a national policy (or global international policy) has immense consequences on the opportunities and outcomes in peoples lives. Both stifle and regiment the lives and actions of people in a myriad of ways (climate change is a massive externality for everyone!), so anti-stifling arguments have no traction. The only arguments that can do real work will have to concern policy consequences: which policy yields better life outcomes in terms of health, wellbeing, longevity and so on.