The allocation condition to be an active employee on the last day of the plan year typically applies to employer contributions such as non-elective contributions or matching contributions (allocated annually). The fact that the last day is on a Sunday is not an issue for employees who are continuing actives.
The common decision a plan administrator has to make is whether an employee formally terminates employment and/or retires on the last pay date (6/28 in the question). Some plan administrators take the position the last day is satisfied if the employee worked on the last available work day. Some plan administrators take the opposite position. Some plan administrators consider the reason for the termination (retirement, disability, voluntary termination, involuntary termination). Some plan administrators look at payroll practices so if an employee is paid for a pay period that includes the last day of the plan year, then the employee was active on the last day. Some plan administrators look at how the last day is defined in their health and welfare plans. Whatever or however the decision is made, it must be applied consistently and uniformly to all similarly-situated employees.
If the plan is top-heavy, the plan could exclude an employee who is not active on the last day from getting the top heavy minimum contribution (if there is one). Again, be careful that the decision is applied consistently and uniformly.