In fairness to Prime Minister Peirre Trudeau, I think you must look at the "time and space" factors: specifically at Québec in the 1930s.
It should certainly not be surprising that Pierre Trudeau, like so many, many young men of his age and societal standing (his father, old Charlie Trudeau, was rich and a true self-made man), was strongly influenced by Abbé Lionel Groulx and his French nationalist and fascist/Nazi/Vichy sympathizing
Ligue d'Action française.
In the late 1940s, having sat out the war in Harvard, Pierre Trudeau went to Europe for further studies and concluded:
a. On reflection, that his wartime
position had been ill-considered and he found himself on the wrong side of history; and
b. On further academic study that
nationalism was the root cause of all of Europe's 20th century horrors. He turned his back on Abbé Groulx and, with a convert's zeal, switched to a leftist position, seeing the USSR,
for example, as the shape of a post-nationalist future.
If you accept
Isaiah Berlin's fox vs. hedgehog theory then Pierre Trudeau was a classic hedgehog: he had one big idea ~ nationalism is the root of all evil ~ and he saw
every issue through that lens.
I think Pierre Trudeau was an intellectual lightweight ~ proof that a first rate education cannot improve a second rate mind ~ and it must have been dreadful, for him, to have to deal with the likes of
Gordon Robertson, Robert Bryce and John Pickersgill, which,
I think, might help explain why he tried to emasculate the civil service, especially PCO and External Affairs and, to a lesser degree, Finance. It wasn't, in my opinion, because he, Trudeau, had other, different ideas, it was because he
hated (and felt inferior to?) the
Oxbridge establishment in those departments.