Can anyone explain this? I think they've glitched under the map

Just finished up a TDM match in social quickplay. Got down to a 1v1 for the 3rd and final round. This guy had only just joined part way through this final round. I had no idea where he was so I was generally just looking around, pushing up to their spawn as I’d seen he had some Longshot kills in the killfeed so I thought I’d cautiously check around then this happened.

Link to clipped DVR uploaded to OneDrive