I'd expect "Readbeard the Blockader" to carry something like a battle axe or claymore.

He was armed with far more powerful weapons ... poor judgement teamed with a lack of self reflection and/or rationalization.
WillyJayBob's perspective is well written and I agree with everything except the dismounted rider. As a dismounted rider ... you get out of the way of anyone still on the bike if possible. You certainly don't turn yourself into an obstacle.
Had that been a pedestrian, I would have expected that they would act from naivete and stopped. I would not expect the dismounted rider on a full suspension bike to suddenly stop where the trail narrows.
I don't scream ... I have a policy against it. But after being landing on your head and having someone feign concern and take no responsibility ... one can no longer contain themselves.
On edit: This is not from a standpoint of privilege... but courtesy. We are out there to have a good time. I'm frequently dismounted and it would never occur to intentionally force another rider cyclist to dismount. In general almost I'd say 99% of all trail users are trying to stay out of each other's way and avoid conflict in the sense that everyone is yielding to each other.. This was an extreme exception where there was plenty of space until someone deliberately stopped at a singular point where the trail narrowed between two trees that left me with three bad choices...
1) hardship and potentially tip over ...
2) attempt to pass in a very narrow gap ...
3) slam into the individual and use them as an airbag
Of course option 3 would not occur to me when when this individual decided to blockade the trail. I was more angry for this guy sticking to "I told you there was a tree down... " rather than listening to why that was an uncool move ... the first I've ever scene it in MTBing for 20 years.