This issue has been raised in the past.
It's especially relevant after Twitter went after some accounts critical of Islamic terror, including ex-Muslim cartoonist Bosch Fawstin, and an Israeli diplomat in Brazil, but continues to host Hamas.
Now Ashley Rae Goldenberg at MRC has somewhat of an answer from Twitter.
While the Twitter spokesperson said she could not comment on specific accounts, the spokesperson directed the Media Research Center to this specific passage of the rules against violent extremist groups:
Exceptions will be considered for groups that have reformed or are currently engaging in a peaceful resolution process, as well as groups with representatives elected to public office through democratic elections.
The exemption goes on to claim that the policy also “does not apply to military or government entities.”
That last part would have covered ISIS.
Hamas is not the only terrorist group active on Twitter.
Hamas has a Twitter account. It links directly to the website of a terrorist organization responsible for murdering thousands of people. And which advocates genocide. Al Aqsa TV, Hamas' tv channel, also has its own Twitter account.
Hezbollah's Al Manar TV also has several Twitter accounts.
Both of these are recognized terrorist organizations. Hamas is listed as a FTO terrorist group by the State Department. Providing services to it as Twitter does, may be illegal.
Arguably the law is quite clear.
the term “material support or resources” means any property, tangible or intangible, or service, including currency or monetary instruments or financial securities, financial services, lodging, training, expert advice or assistance, safehouses, false documentation or identification, communications equipment, facilities, weapons, lethal substances, explosives, personnel (1 or more individuals who may be or include oneself), and transportation, except medicine or religious materials
Twitter has been repeatedly notified that Hamas is using its services. Ashley's interaction with a Twitter spokesperson is a corporate response. The company is now officially aware of the situation and has indicated that it intends to continue providing material support to Hamas.
The company is in violation of the law. The question is whether the DOJ will enforce the law.