Twitter is perfectly free to do that, but is not compelled to do so (and still won't be even if EFF wins this lawsuit).
Also notice that EFF winning this lawsuit will not compel all gov't users to disavow the block feature, because not all forms of gov't communications come with the same free speech obligations. The 1st amendment has different ramifications depending on the purpose of the forum; e.g., the rules for:
* NOAA emergency announcements,
* national park service informational billboards, and
* city council Q&A sessions
