The referenced article states that you cannot perform DBCC CHECKALLOC or DBCC CHECKCATALOG on tempdb. I presumed that since DBCC CHECKDB performs both of those functions (cf. http://technet.microsoft.com/en-us/library/ms176064.aspx), one couldn't run DBCC CHECKDB against TempDB either.
But, there's a line buried in that article saying,
"Running DBCC CHECKDB against tempdb does not perform any allocation or catalog checks and must acquire shared table locks to perform table checks. This is because, for performance reasons, database snapshots are not available on tempdb. This means that the required transactional consistency cannot be obtained."
So, special handling for TempDB.
Always read the fine print....