Please note the sole purpose of trademarks is consumer protection. Protection from counterfeit goods and services, where `counterfeit' means coming from different source than the one the consumer expects due to branding the goods or services bear.

Now ask yourself (or even better, Twitter), `were consumers being deceived, or at risk of being?' `Is account name an instance of use of any brand?'

I believe Twitter should just follow the standard practice of using ™ and ® (TM and (R)) symbols for visual identification of accounts that are representing trademarks.

>> Please note the sole purpose of trademarks is consumer protection

Not true at all, although it's easy to understand why someone would wish that this were the case. The sole purpose of trademarks (really trademark law) is to protect the holder of the intellectual property.

Market confusion is a test used to determine whether a trademark infringement has taken place, but it's only one of several possible tests.

the problem being that "Tower Bridge Exhibitions" is not a trademark owner for "Tower Bridge". It actually seems like they are stomping on other companies trademarks by claiming the base name"Tower Bridge" when they don't have it as a registered trademark in any field of endeavor.