Well, I think you’ve swallowed wholesale 19th century apologetics for European imperialism.
Military and naval officers for all the European powers were constantly looking for pretexts to expand their country’s colonies and make a name for themselves. When they didn’t happen naturally, they weren’t above manufacturing them.
The murder of a few priests, while deplorable and appropriate to punish, is not exactly a valid reason for conquering and ruling an entire country for a century.
No, I've actually studied the historical circumstances of colonial activity.
French Indochina was not the Belgian Congo, nor was it Jamaica.
The default assumption is that all colonies began with mass murder and wholesale enslavement.
That's how Japan's Co-Prosperity Sphere began, but not how every empire began.