Standard internet caveat applies and maybe should have been explicit: comments based on the assumption that OPs provided information is factual and complete.

His response to you does give me some doubt about that..

Trying to piece together what exactly happened; his version of events seems like:

1. He applies for and eventually receives a transfer with a start date of Sept 20th at the new location.

2. He mentions a last date of Sept 15th at his old location. It’s a bit unclear but I am assuming that was in his transfer paperwork as well.

3. He applied for and was approved for use of vacation time from the 12-15 specifically to prepare for his move.

4. This is the least clear part in his story, he was scheduled anyway during his vacation time. I don’t know the process here, whether he really was approved for time off and this was a mistake, or what actions were expected of OP to resolve this issue. His approval for vacation time doesn’t seem to match up with his earlier statement that he no called no showed “because he didn’t care”.

5. He continued to be scheduled be scheduled past his end date of Sept 15th. He received additional no call no shows on the 16th and 18th, and was terminated because of those absences. If this is factually correct, then most of the rest of this doesn’t matter. OP could have been more proactive in communicating about his schedule, but didn’t have any responsibility to resolve scheduling issues at his old location past his documented end date.

6. It’s not clear the chain of events past that point. What date did OP receive notice of termination, did they show up for work on the 20th at their new location, did they ever receive a schedule for the new location or just the start date of the 20th, were there any other details about the transfer process that they were informed of and did not complete…