That thread's talking about SELECT and the locks it takes. You're talking about UPDATE. Very different locking behaviour in the default isolation level.

In read committed isolation (the default), shared locks taken by selects are released as soon as the statement completes (sometimes earlier), while the exclusive locks taken by insert, update and delete are held until the end of the transaction.

And yeah, unfortunately not everything posted in the forums is true. You have to consider the poster's history and check more than one source to be sure (or test if it's something testable).