Absolutely not true.  Whites oppose the Alt right/White Nationalists movement.  Opposition to White Nationalism is a matter of principle and conscience (by BOTH whites and people of color).  Support of White Nationalism is nothing more than naked racism against non-whites.
Obama's only contribution to the rise of the White Nationalist "movement" was the coincidence that he happened to be black.
White Nationalists' reaction to Obama was pure racism.  Based on his immutable racial trait.  Certainly not based on his policies.  Certainly not based on his political patronage practices, certainly not in his policies, and certainly NOT based on the way he manned the US government during his administration.
Blaming this in any way on Obama is merely buying into, projecting and promoting the abject racism that ever suggested that a non-white President is anti-white.
The problem here is white racism against non-whites.  Plain and simple.