Why is that ridiculous, we don't know what was said.
It would be really easy to write a pre dinner prayer that could end up with a police hate speech investigation. Full on Westbro' Baptist style, or Pastor Kevin Swanson ( him of drown gay people fame).
And these folk who could be called Christian fundies, or extremists, would not be making anything up, because it is all in the Bible.
Check out what Paul said in Romans 1:32 " Who knowing the judgment of God, that they which commit such things are worthy of death, not only do the same, but have pleasure in them that do them. " (KJV)
And now look up the list of things in the previous verses that Paul considers crimes worthy of death. It's a long list.
For sure, folk can point to this post and say, " Look, we seem to have an atheist cherry picking the bad bits from the Bible". To counter that, I would just point out that it is not me cherry picking, It's the people who say the Bible is all love and peace who are doing the cherry picking.
So yeah, I can certainly see how Christian prayers at a secular function could be seen as problematic.