For what it's worth, I dealt with his pension payments (also a university scheme) on the income tax by returning his gross annual salary i.e. I just didn't claim any deduction for his contribution. Like you, his salary was always covered by the Foreign Earned Income Exclusion. I didn't gross up to try to account for the employer contribution.
Since he has renounced already and no longer files a US return, the following is no longer relevant; but for anyone still in the system, the following may be of value.
By virtue of your reporting his own contributions to the pension scheme (gross salary reported on FEIE), IMHO, he now has a 'basis' in the pension. If funds were deducted from his salary for the scheme, then he has declared those funds for tax purposes and should not be taxed on those funds contributed when they are withdrawn as part of the draw down benefits. He should be able to proportionally reduce the amount of his yearly benefit for tax reporting on 1040 (line 16b) by those pre-taxed contributions. Where foreign pensions are involved, the method of achieving the correct amount (determining the proportion of his basis) is by use of Publication 939, general rule for pensions and annuities. There are worksheets in 939 to make the calculations. 939 can not be of any benefit until one knows the exact final yearly or monthly amount which they are entitled to, as well as other final yearly income amounts. But you need very accurate records for each year you made contributions that were declared for US tax purposes, and the exact yearly amounts.
For US Qualified pensions, you are allowed to use the simplified method on line 16b to calculate your basis (the amount to reduce). Since foreign pensions are not qualified, they must use the general rule to find the reduction.
This is my amateur opinion, and others may disagree with this.
I have to say that our US tax life became more complicated when he retired and had only unearned income - as pensions are classified.
I agree with this comment, 100%.