Yes, it's an optimisation, SQL caches the definition and a single data page to reduce the work required to recreate it. The table variable's effectively gone, you cannot access it in any way, there's just a shell cached for future use.
Why is it a concern?
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability