You are underestimating her. She knows exactly what she is doing, same as she did when she refused to call Assad a war criminal. Collusion is a catch-all term the GOP and Fox crammed down everyone's throat. It encompasses several crimes, including conspiracy. Mueller found evidence that Trump committed a crime, but not enough to charge him. However, no amount would have been enough to charge him, because OLC prohibits charging the President with a crime while he is in office as we've discussed on this thread for months.
Given those constraints, Mueller is very clear when he reiterated it to those that missed it the first go around. There is reason to believe that Trump DID commit a crime, but not enough to charge him. Tulsi is intentionally spreading disinformation for the GOP.
"As I said forth in the report after that investigation, if we had had confidence that the President clearly did not commit a crime, we would have said so. We did not, however, make a determination as to whether the President did commit a crime."