What are you gonna do about inactive accounts that were not downloaded from Xbox 360 to...

They haven't said they'll do anything with those. It's not the same as when they released inactive accounts from the original Xbox. Since accounts can be used on other Microsoft services, even if they're not in use on an Xbox, they may be in use elsewhere.

Look I clearly said,”Alternatively, I have noticed that the account "Lnk" seems to be inactive.” And if you were to check on Xbox the name LnK has 18 friends, no gamer score, and no games played with a Xbox 360 profile picture. I’ve heard rumors and seen people exchange usernames from inactive accounts on Xbox, they use auto claimers and wait for Microsoft or Xbox to either ban the account or the name due to its inactivity, then the auto claimer takes the user and adds it to a different account. I was just wondering if there was something else I could’ve done rather than doing what I had just stated.

The expired gamertags they were referring to were gamertags from the original Xbox system. Microsoft freed up any gamertags that were never recovered for use on the 360 and were still inactive. Otherwise no matter how long the account's been inactive, it
will still be on the server unless Microsoft changes their minds in the future. But I'd say you'd be safe until there's a new console.

Most of the ones that were inactive in previous resets were gamertags that were created on the original Xbox and had never been migrated over to the 360. Other than that, I'm not sure what other criteria they used to determine which ones were released
although not all inactive tags were released.

Around two years ago, they released about 1 million gamertags that were from the OG Xbox era and never migrated to 360.

Shortly after that we found out that gamertags will be released after 5 years of account inactivity.

Since then, I don't think they've said any more about releasing gamertags.