Suspicious but not enough to ban IMO.
Part of the issue is it being a small map and could have done with a longer demo.
If I suspect someone of hacking, I generally don't warn as it draws attention to the fact they are being watched. In this case, I would also spec them the following map too. My rotations all have smaller and larger maps interspersed to add variety. It is easier to spot WH on larger maps, so if you wait one more map you will have a better chance of getting a 'conviction'.
I know it can be frustrating when a player is breaking rules and other players are whinging and you want to play yourself, but a bit of patience is sometimes needed to get a cheater off the server forever.