Maladaptive if you only focus on reproduction itself, which is a very close minded way to look at evolution. Plenty of behaviors dont directly improve your reproductional fitness. This reductionist understanding of evolution fails to explain many things like altruism. Life is complex. Homosexual behavior can have many positive effects on a population, for example: social bonding, grooming each other, literally practicing sex, or raising abandoned young. In that sense there are many reasons why homosexual behavior might have a positive effect on a populations Fitness.
But even if it didn't: actual maladaptive behavior isnt any "worse" then is the actual adaptive behavior. Its just a different way to live. A black widow that isnt into being eaten after sex might live a very long life compared to its brothers, it just wont have any babies. This is what social darwinists get wrong about evolution. Things being maladaptive is a consequence of natural variability in a species. This variability is what makes evolution possible. If somehow, for whatever reason the Environment were to change in a drastic way, making homosexual behavior even better for fitness (in theory), a species without any homosexuals would die out, while one with homosexuals will live on. People being different isnt a bad thing.
Even if there was no advantage to being gay, trans, autistic or whatever (in reality there are of course advantages), and being this way had only negative effects on fitness, evolution works by natural selection. It doesn't produce "perfect" organisms. It produces organisms that exist. If that existence goes on to another generation it does. If it doesn't, it doesn't.
Evolution isnt about "survival of the fittest". Its about reproduction of the reproducer.