They are full aware of it:

"Android Studio should currently not be used for development with sbt and Scala. Chances are, however, that it's a good fit for a Gradle + Scala setup."

http://scala-on-android.taig.io/editor/android-studio/

Using InteliJ instead of Android Studio means not being able to use the latest tooling even from the stable version, as InteliJ is always some versions behind.

Using Gradle + Scala implies a few configuration steps that tend to break at each new Android Studio release, versus the out of the box experience from Kotlin.