Note to other site members: There was excessive disruption, argument and rudeness in comments that have since been deleted (and elsewhere) i.e. you cannot now see the whole picture.
I knew that my actions in this case were quite likely to result in a question on Meta, and you have done that, so thanks for raising this and for the opportunity to explain.
Is it the OP's fault his question is "locked-out" for 7 days due to arguments in answers
No, it's definitely not the OP's fault, but in a fast-moving situation, a mod's responsibility includes stabilising the situation by any means, to prevent things getting worse. That is why locking posts is given to us as an tool we can use, when we believe it is appropriate.
Locking the topic was not my first action, and was not done lightly. However leaving any part of that topic unlocked last night, would have allowed the arguments to continue in that part (comments or answers). Therefore I make no apology for doing what I believed was necessary, at that time and in the best interests of the site, to prevent the thread from becoming even more argumentative. In that situation, I would do the same again, while working on other measures behind the scenes..
Of course it is very regrettable that any moderator actions have side-effects on innocent site members like the OP, and I am acutely aware of that.
Sometimes situations need time to resolve. Just because site members don't see things happening, does not mean that nothing is happening. Sometimes we need time to research, consult our notes, consult with other moderators, consult with Stack Exchange staff, write messages etc. (also to drive, sleep, eat...).
Note that the time that a mod locks post(s) is not "set in stone" - it can be modified (either extended or shortened). In this case, my plan was never to leave the topic locked for a week, but there are limited options that we can choose from (1 hour / 1 day / 1 week / permanently) and I had reasons for choosing that one. Again, the responsibility of a mod is to stabilise the situation first, using any and all available tools.
As I explained in a comment:
I'm locking the whole Q&A while considering the next actions and to give time for people to calm down.
I have been working "behind the scenes" and things have moved on since I locked that topic. My plan was always to leave the topic locked for shortest time, but which was consistent with dealing with the cause of the (now deleted) disruption. I have now re-opened the topic.
However, if comments or answers become argumentative again, then a moderator will take action. There have been many comments on the question, perhaps too many. Moving them to a chatroom would have the advantage of them not being "in the face" of visitors to the page (which is one of the reasons that we can move comments to chat) but doing that also makes it more difficult for mods in some ways. So comments have not been moved to a chatroom, yet, but they might be in future.