UMLR — Restrictions on decision nodes

In activity diagrams, the input and outputs to a decision node much all be control or object flows. However, I’m not sure why I need to have that restriction enforced. I can see that if the input is control, no output can be an object flow (because how would the object flow be generated). However, I can imagine cases where an input object flow is evaluated, and

1) If the Object flow is good, the object flow is then passed to a downstream activity

Or

2) If the object flow fails, a control flow is sent to start an error recovery activity, but this activity has no need for the object flow in error

I would imagine the correct restriction is that If the input flow to a decision is a control flow, only control flows can come out of the decision.