If you remember the beginning of Iggy's mainstream success, people criticized her for her rude reaction to Q-Tip and his well-meaning lesson of hip-hop that was directed to her. When she started receiving backlash for playing the victim, T.I. (and several other opportunistic male rappers) swooped in to coddle her.
However, T.I could only stand up for
"In her defense, she had a lot thrown at her at one time. Any human being anywhere gon' have a hard time adjusting...Some stuff they brought upon themselves. In some cases it kind of was just the easiest place to put some pent-up aggression."
"After the Q-Tip thing....After I kind of had smoothed it over, like okay, 'What is really meant to be said here is...' After it was cool, everything was cool, and then they kind of came back and undid what I had just [accomplished]. I'ma be all the way real: I'm a loyal partner. If I rock with you I'm gon' rock with you...I really do feel that they just needed a little more time to adjust, which I feel they can do. They have the talent, they have the charisma."
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Source
tl;dr - He got sick of cleaning up all her Twitter whining messes.