In the business of publishing, few publishers handle all genres. They find what they are good at, what sales support, and they focus on that. For example, you would never query a gripping horror story to Harlequin.
A publisher only wants to spend time and resources on something that is their best guess will sell well. Otherwise they are wasting money.
Editors also enjoy working on what they enjoy reading. Someone who savors cozy mysteries is not going to only dislike working on a sci-fi epic but their knowledge base, word-craft, and editing will likely be negatively impacted because it's a subject matter they have little experience in.
Consequently that is what the judge meant by "isn't a good fit for Tapas genre-wise". Not only would a historical alternative fiction not sell well on Tapas, the judge likely did not enjoy the subject matter. This was just their way of easing the blow of rejection.
(Not to mention that fabulously negative rejection letters have a way of coming back to bite you.)
Whether intentional or not, Tapas has become a romance and LGTB publisher. It is simply a reflection of the reader demographics of the site/app at this particular time. The current standings of the contest confirms that as well as The Boy Princess being the only entry from the last contest to make it to Premium.
Unfortunately, given the current readership, a disparity exists where stories outside romance and LGTB have little chance of success in the popularity game.
Which is why in retrospect this contest should probably have been genre-based or assigned a point system where certain genre receive a weighted handicap to level the field.
Regardless, we're still going to finish our 5,000 word thriller entry even though continuing to participate appears a forgone conclusion. We ran across this tweet earlier this week and it gave us the strength to press on when we almost threw in the creative towel.
You should write what you are passionate about, even if it's not going to win, even if people ignore it, because your story is your story. Just because Tapas readers like A and you like B doesn't mean your story isn't "quality content".
Eventually Tapas' novel arm will develop a larger reader base and your title will find its following. The best thing you can do is press on, enjoy the process, and do the best that you can do for you. If you keep doing 250 words a day, in a year you will have an entire novel that you can then take to an agent and shop around.
Just because you don't end up successful on Tapas does not mean you can't be successful with another publisher.
Stay the course.