Natural immunity and "vaccine immunity" are not the same. There are real risks to vaccinated people thinking they are safe and not a danger to others. Their bodies may contract a subclinical infection which they spread. They may "shed" virus or proteins that are hazardous to others. Also, their bodies may become "factories" for mutant strains as the target strain is inhibited. All reasons for unvaccinated people to be safer to be around.
The vaccinated seem at greater risk of contracting variants. Due to the possibility of antibody dependent enhancement they might also react badly to subsequent exposure after their jabs.