The fact that c-suites authorize buybacks largely to boost the stock price in order to trigger their own performance bonuses tied to the stock price only highlights that point.
If you did something even remotely similar, you would be prosecuted for fraud, because it's fraud.
1) Wrongful or criminal deception intended to result in financial or personal gain.
2) A person or thing intended to deceive others, typically by unjustifiably claiming or being credited with accomplishments or qualities.
The problem though is that the incentive structure is so that none of the involved parties has any disincentive, let alone an adversarial incentive to end the practice, let alone has standing to do anything legally, short of sabotaging their own stock value.
It's a totally perverse and corrupted incentive structure, similar to why both Trump or Biden, or Democrats or Republicans have the real will or interests in ... non of the involved parties have any interest in revealing the rot and corruption, and all parties involved have every incentive to keep it all under wraps, suppressed, covered, up and distracted from.
In some ways, a civil activist organization could in fact buy a single stock of one of the most egregious stock buyback stock price inflation causing corporations and sue them for fraud and deception, but it would have to come with a claim at manipulation of the market due to fraudulent manipulation of the price discovery process similar to a light version of cornering the market through restriction of supply, i.e., cartel behavior.