I think this approach sounds good. At first, it protect users from reading shitposts from bots, and the solution to hire new staff(s) to do it is great. Spams from bots are easily to realize, normal users can realize them too. With current report tools of the forum, yes, forum users can reports spam from bots, but it takes time to report, then wait for handling from staffs. It takes time, sure. I don't think we should allow such things freely pop-up without control at the start. Prevention is always better than cure!
As I already said, more staff could be added to meet demand as well. You could even have one or two staff who's sole job was to handle them. I'm not saying it's perfect and there are pros and cons to any spam measure, but at least this pretty much stops the bots nearly 100% from being an eyesore and infecting the forum.
One more thing, if forum has reporter badges (that theymos asked for designs and ideas months ago), I do think that community will sure more eagerly to report.
Again, I don't think it will take that long to verify them. Most urgent reports get handled very quickly and it's only stuff like sig spam reports that tend to stay in the queue long-term or don't get handled. I don't think we'll ever get 1000 brand new accounts posting after the other but I can't tell you exactly how long it would take or how much workload it would add but I think people are exaggerating or being overly cautious on the issues it may cause but if it did become apparent that it was causing a backlog or strain on moderation I'm sure there's plenty of willing people who would make good patrollers to help verify them.