Probably not, but read the actual rules to be sure.
Rest and Meal Periods:
Rest periods of short duration, usually 20 minutes or less, are common in industry (and promote the efficiency of the employee) and are customarily paid for as working time. These short periods must be counted as hours worked. Unauthorized extensions of authorized work breaks need not be counted as hours worked when the employer has expressly and unambiguously communicated to the employee that the authorized break may only last for a specific length of time, that any extension of the break is contrary to the employer's rules, and any extension of the break will be punished. Bona fide meal periods (typically 30 minutes or more) generally need not be compensated as work time. The employee must be completely relieved from duty for the purpose of eating regular meals. The employee is not relieved if he/she is required to perform any duties, whether active or inactive, while eating.
Was the employee's attendance to the luncheon mandatory? If yes, I would pay the employee. If it was voluntary, I would not pay the employee.
And if attendance if voluntary, make it very clear that is so. I have had employees claim otherwise, sometimes with cause, where the company is saying one thing when the supervisor is saying something else. I sometimes think the primary purpose of supervisors is to jack the company up with the government.
and there is "voluntary" and then there is VOLUNTARY (really mandatory but don't want to pay them). Make sure no pressure is put on the employee or that important information/training isn't missed and held against them. Or "voluntary" is really VOLUNTARY
Maybe send a second memo to the supervisors only explaining just what the word "voluntary" means. Reminds me of the Princess Bride movie where one guy keeps saying the what their pursuer doing is "impossible" and finally his buddy says "I do not think that word means what you think it means".
"Inconceivable" - "You keep using that word. I do not think it means what you think it means."
I stand corrected. Good movie.