I'd be more inclined to see your point, except that the manager in question said "each job requires 2 weeks notice" like he was indignant that he didn't get something he deserved.
That's not only not true at all, it's active manipulation on their part in a hail Mary attempt to have their work covered for enough time to look for another employee.
It may be unprofessional to quit without notice, but it's really unprofessional to present the act of quitting as requiring 2 weeks' notice, particularly in a place that might also allow the employer to fire someone for any reason at any time with no notice.