Reducing compensation / increasing employer contribution

Employer establishes a church plan and doesn’t elect ERISA.  Pastor is paid $100,000 a year; with a 10 percent employer contribution to a 403(b) plan.  Pastor is expected to be paid this amount for each of five years.  In year one, past says, don’t pay me $100,000 in year 2; pay me $90,000; and the rest as an employer contribution so as to total $110,000; In a similar manner, in year 3 pay me $80,000 and year 4 $70,000 with the remaining amounts in employer contribution so as to total $110,000.

What, if anything, is wrong with this design?  

Might the pastor's choices be expressed in the form of a salary-reduction agreement that states a proper elective deferral?