Unsurprisingly, the Tower Tavern is located right next to the BT Tower. However, I think it’s a very bizarre name for a pub. Pub names in the UK can be based on a variety of things such as animals, heraldry, colours, transport, historic events, etc. Location is also commonly used for naming pubs, but usually not something so recent.
Still at the end of the day, probably not worth thinking (or writing) too much about. Besides, the pedant in me would point out that the image of the BT Tower on the sign is how it used to look (with satellite dishes), so in a sense it’s at least using historic imagery.