BUG: ship to road without settlement between

I recently played a game of C&K/SF and an opponent with two ships coming from a settlement on the main board placed an army/knight on an island hex and then proceeded to build a road from that spot w/o having a settlement. The spot of that army/knight was built to prevent another player from continuing their road past that point, but the road afterwards totally prevented any attempt to challenge the knight and build past that player.