Yes. If a guest comes back from a ride injured (beyond things like head banging) you should (IMO) stop operation to find out why.
I completely agree as well. As the saying goes, safety first. And I'm not quite sure, Tmcdllr, what you mean by "every time somebody complains 'like this' because I don't know of any other complaints like this. In my opinion (and I don't see why this is even a debatable issue), someone getting hurt on a ride (as Comeagain stated, outside of something like headbanging) is serious and should be taken seriously by the park. If Disney, Universal, or Knott's received a complaint that someone was hurt from an obstruction on a ride, you bet they're going to shut down the ride immediately.
And to the argument that rides would never run if they addressed complaints whether they were made up or not, well look, Ninja can't run AT ALL right now because they didn't look into something they should have.
I agree too, safety first, and if there is an obvious injury such as bruising or bleeding then yes, do the inspection now. But I'm sure the parks get guest complaints all the time of alleged 'injuries' on rides with no obvious signs of the injury and in that case, should they then stop the ride and inspect it every time that happens? Maybe it depends on the alleged injury, I don't know, or, does this even happen often enough- real or fake, to even cause a problem? What do you guys think? I'm sure they are many of you that have visited parks more frequently than I have so what is your take on this, have you seen such an incident before?
Working in this industry, yes, if someone has a complaint that seems to have merit (obvious harm, not just "It was scary!" type harm) then we will most definitely hold the attraction until we can investigate it further. Sometimes that involves walking it, sometimes that involves actually riding it. Hell, even if there is an odd sound on an attraction it will prompt us to hold & investigate.
The Big Thunder Mountain accident at Disneyland years ago was a failure of maintenance and training. The ride ops knew of an odd sound coming from the train whilst in motion and continued to load the train before the accident happened that killed someone and hurt a score of others. Safety is the utmost importance. All rides should give the illusion of being unsafe, but if it is unsafe for real reasons, then the park has failed its patrons and given them real risk, instead of a perceived one.