Yeah that must be it.Or trying to artificially suppress demand.
We are talking (almost) a year away. They have nothing to lose by offering high fares now to those that are so desperate to plan this far out they will pay anything, and then adjusting the fares downwards later if it the high fares are not selling.
Conversely, it would be stupid for them to sell out with cheap fares now when someone might come along in six or nine months who would have been willing to pay more, but nothing is available. n fact, this is what they would do if they REALLY wanted to kill a train by showing low revenue.