Why? You don't think someone can have had excellent personal character while still being a product of a time and place that inculcated harmful group chauvinism? Might as well throw out all of Greek philosophy with that attitude.
See the poem, (and play, and film adaptation - which is a moving depiction of his experience of his son being killed) my boy jack.
Although as for "product of his time" and WW1 poetry in general, remember that Wilfred Owen was writing around the same time and is very much ahead of many warmongers to this day. People are products of their circumstances, cultural and temporal.
https://www.poetryfoundation.org/poems/46560/dulce-et-decoru...
A friend of mine's great-whatever apparently confessed on his deathbed to having shot his commanding officer who had begun summarily executing retreating soldiers for deserting (i.e. not walking directly into a wall of machine gun fire)
That being said the former viewpoint is still being elucidated to many people so I am not overly critical of those who express it too enthusiastically.
The Mythos of Churchill must be challenged, just as the good celebrated and analysed.
Very few people seem to know of Clement Attlee these days, which is probably a tragedy considering his influence on what really matters in Britain today.
But yes I'm quite against the tendency to crucify dead people, which is annoyingly prevalent in some circles.