Hodl contracts allow a third party who both counterparties trust to determine the outcome without taking custody of the money (because they are just a routing node).

I hope you see the difference now. Instead of paying your counterparty directly, pay them through a routing node that will forward or cancel the payment based on the outcome of the game. That's what distinguishes hodl contracts from hodl invoices.

But the max HTLCs in flight thing is pretty easy to solve -- just open up another channel. The max HTLC limit is something like 425 htlcs per channel, which seems like a very high number to me, especially because, if they are all in use, that means your service is very popular, so you can probably easily afford to just open up another channel and get 425 more HTLC slots.