Activist investors pressure management to improve. Most activists are funds and are accountable to their investors. The investors and ultimate beneficiaries are institions such as the Public School Employees’ Retirement System.
Activist investors pressure management to deliver more profits to investors. That's a narrow definition of "improvement". Doesn't matter who they represent, robbing Peter to pay Paul doesn't make you right.
"robbing Peter to pay Paul" is an idiom used to express that causing one person harm to benefit another is not a good thing. When an investor forces a company to lay off staff, merge with another, sell off divisions, etc... (all actions TCI has done) people within those companies get laid off, their jobs change, wages stagnate, etc... and this is purely for a fund's enrichment. For me it doesn't matter if that fund is then donating to charity because I don't think charitable use of a fraction of profits justifies harmful tactics used to raise that money. That'll just have to be a difference of opinion between us.
If you want to move the goalposts from TCI to activist investors that try to improve a company, then that is a different thing as profit is not the primary motive of those changes. There are activist investors who simply do not invest in companies they do not agree with and in other companies try to address issues with how the company runs, pay gaps, tax compliance, workplace conditions, etc... This is actually trying to improve the company and the lives of the employees, at a possible cost to the company and investors, so very different from just trying to improve a company's profits. Ethical capitalism is a bit of an oxymoron but there is definitely an ethical spectrum of actions within capitalism. Not all actions are equal.