Respond how exactly? The last thing you want to do as an organization like this is to take action and then find out that the removal was warranted. I think it is up to the app developer to supply sufficient information to show that it was not warranted.
In another posts, someone already showed where they are essentially uploading contacts to remote servers. I agree it sucks cause I had seen the app on F-Droid and it looks like it was actively developed, but the developer stopping development because of the Play Store removal doesn't help instill confidence. Otherwise, they'd just continue development and support F-Droid and alternative Play Store initiatives.