If you don't think a baby deserves to get raped, then I don't see what raising the issue of its innocence is. It is innocent enough not to be placed in harm's way like that.
I chose a baby because often taking most clear examples can highlight problems with philosophical, religious or moral stances that are harder to see with other examples. I do not think it is OK for adults to get raped, but I don't want to get distracted by some of the issues that can get raised around adults. With babies most of these are immediately eliminated. We have someone utterly dependent on the adults in the home God has placed them in. Regardless of the choices the baby makes it cannot defend itself. It has not been bad so one cannot see the rape as something it has brought on itself, somehow, morally.
Since we are dealing with God, all examples must be covered.
To give a kind of opposite example to babies can perhaps show why I chose babies:
Why does God allow prison inmates to get raped?
You can imagine how the discussion might go all over the place to issues that do not apply in the situation with babies. I could have also used an everyday non-criminal adult. An example 'in the middle' so to speak. But even there it is muddier.
I chose the one where the issues I want to highlight are most clear.