Jynthea, I fully understand your frustration in all of this. The key element to the 330 day physical presence test is that it has to be 330 full days in a foreign country (travel days do not count) within a 365 day period. This is a very black and white rule in that 330 days you get the full exemption whereas 329 days you get nothing.
The 365 day period does not have to start on any specific day. The key is that whatever day you select, he has to be in a foreign country for 330 of those days. If there is any way to select a 365 day period that meets that requirement then you are good to go. Unfortunately, from what you described, I don't think you will qualify. If he deployed in March 2020, spent roughly 6 weeks home in OCT-NOV, and then stayed until the end; I just do not think there is any 365 day period that will give you the required 330 days. You will be roughly 15 days short if my math is correct and I know that is not what you wanted to hear.
Hindsight being 20/20, another thing you could have done was spend time in a foreign country during his vacation. If during his 6 weeks home you took a vacation in a different country or countries of your choice for 3 weeks then then those days also count and you would make the 330 day rule.
Sorry to be the bearer of bad news.
