Two separate things here. Recruiter tells me you are exploring enlisting which means you will go through MEPS. DoDMERB, as referenced here, is a separate path with its own regulations. Although there is a lot of overlap, they are two separate items with two separate set of regs, waivers, etc.
I had a close friend’s daughter who was able to enlist with a thyroid issue. Based upon the research I did then and walking through that process, hypothyroidism that is controlled with meds can get through. Controlled will be the key and will be what is scrutinized. How long one has been diagnosed, on meds and what the TSH results results showed were the keys to getting through the process. She had to wait to enlist a few extra months because they wanted to see 12 months on medication and had to have several TSH tests completed. Each service will scrutinize this differently, it’s best to have your medical paperwork in good order to show diagnosis, how long on meds, etc.