I more get the impression that he's just not trying to mince words.

His statements of his thoughts and his perceived reasons for social isolation are expressed bluntly and succinctly.

It would have been more socially acceptable for him to preview all of his good points with disclaimers about how wrong he believed himself to "probably" be, and we probably would have understood him as expressing social deference rather than actual uncertainty, but I get the feeling he's focusing on appealing to LW's reputed value of truth and meaning, and cutting out the niceties for brevity's sake.

All of which I personally approve so long as he's aware of it. It could be a stumbling block to communication in other forums.