Is a lapsed Advanced Ground Instructor certificate acceptable to use as proof of FOI when taking CFI initial? I have an AGI certificate that I haven't exercised the privileges of in the preceding 24 calendar months.

When I initially got the AGI, I had planned to take my CFI almost immediately but didn't. I'm having trouble locating the regulation that shows that since I have my AGI, I don't have to re-take the FOI written to complete my CFI.

What regulation states that this is possible?
That would be 61.183(e)(1):

To be eligible for a flight instructor certificate or rating a person
must:
(e) Pass a knowledge test on the areas listed in Sec. 61.185(a)(1) of
this part, unless the applicant:
(1) Holds a flight instructor certificate or ground instructor certificate issued under this part;