They do pull stuff out of their backsides when the fancy hits.
The best argument against limbo is that even though infants and children may misbehave, they cannot commit sin due to their lack of capacity for moral reason. That being so, after baptism removes original sin, infants and young children enjoy a state of grace that assures immediate entry into Heaven.
Oddly, the Albert Brooks movie Defending Your Life takes the same approach with children going directly to Heaven. In other words, a Jewish comedian seems to have followed the best Catholic reasoning on the subject.
Sincerely, how does your faith treat those issues?
It beats evangelicals who curse their children to the fires of hell because they weren’t allowed to be baptized until they make their own mind up and died before that absurd date. Nice folks.
Ol’ Popes Pius IX and XII were the masters of the craft.