The text makes it very clear that the author is disappointed with some action taken by Stephen Mackaye who was someone to whom he had great consideration that turned into indignation.
The passage in the text that makes this indignation more evident is
: "<em> I always sized Steve up as a square man, a kindly comrade, without an iota of anything vindictive or malicious in his nature. I shall never trust my judgment in men again. Why, I nursed that man through typhoid fever; we starved together on the headwaters of the Stewart; and he saved my life on the Little Salmon. And now, after the years we were together, all I can say of Stephen Mackaye is that he is the meanest man I ever knew.
</em>"
