The canonicity of Vikings is up in the air, as I do not believe there is anything that explicitly confirms if it's canon or non-canon... And because some MAX titles are canon and some are not, the series can't be ruled in or out that way either.
"The Grand Admiral was smart and subtle, but never used his brilliance to show up or humiliate anyone.
He demanded results, but never perfection, and had amazing stores of patience for those who were truly working to their fullest ability.
It was a pity Thrawn's style of leadership hadn't spread through the rest of the navy.
If that happened, he suspected, the Empire would stand forever."