No its not a thing. There was no white-knighting of Tulsi. The only thing that happened is that right wingers were also watching the primary debates and were coming to the obvious conclusion that Tulsi stood the best chance against Trump in a general election. Some never-Trumpers latched onto her, but their opinions are at the absolute height of irrelevance.

Her chances against him in a general election had less to do with her policies, and more on her willingness to sink to Trump's level when debating him, and the relative ease at which she does so.