I could imagine that the hover-over name feature might be disabled for output with a large number of nodes like this.
You can file a suggestion with the Wolfram|Alpha team. To do so, make the same query which produces the produces the problem, then at the bottom of the page, where it says "Give Us Your Feedback:", provide a brief description of the problem that you see Wolfram|Alpha's results.
You could also make this network graph using Mathematica, which has a number of functions for SocialMedia data analysis. The great thing about Mathematica is that you can highly customize your output using the Wolfram Language: