Inactive Microsoft Account

Damn it. The account has been inactive for at least 8 years.

When does Microsoft deem an account inactive long enough to warrant that "purge" of inactive gamer tags?

Adding to this, just because it is inactive on Xbox, does not mean that the Microsoft account is inactive. As long as they keep using the account, then the gamertag will stay attached.

An account has to be inactive for two years now, before the account is closed.

Look into it for what? If you're wanting the gamertag, there's no way to take it from another account that has it. With the new gamertag rules, you can still use the tag, but you'll be given a suffix. Otherwise, even though the person may not be actively using an Xbox, they may be using other Microsoft services.

Hi, sorry to say that a gamertag cannot be reserved.
A gamertag will get released if its corresponding Microsoft account is inactive for 5 years; however, the user of an account might still log in on other Microsoft services besides Xbox, and if that's the case, the account would not be considered inactive.

Hello,

Microsoft has stated previously that an account must be inactive for a minimum of 2 years before being designated as inactive. After that period, the gamertag can be reclaimed by a new account. Before then, there is no way to claim the gamertag if it is
linked to an account that has not been inactive for two years.

I hope this helps and sorry for the inconvenience.