Seems to me that he proved himself with development of a digital marketing system to help DJT win.
The principal was to use social media and establish which adds were working and where money did the most good.
In theory, this data led to the Trump victory and the famously lean campaign expenditure.
So proving himself needed to be not to conservatives, but to Trump.
That actually might weigh against Kushner in this case. Historically, you’ll probably find that political campaign advisors rarely stay around as administration officials after their work is done. I was surprised to learn that James Carville, for example, basically disappeared from the Clinton team after he played such a key role in 1992.