That's 100% false. Any insider can buy as many shares as they want. BUT, They have to file a Form 4 within 2 days. It happens everyday with hundreds of companies. They have to file a Form 4 if they sell any shares also.
The kicker is they can't sell any of those shares for a minimum of 6 Months, so they can't use it for a Pump and dump like companies like this.
You are confusing that law for anyone that is not part of the company.