Hi @cryptospeaker,
If the idea is to create post and set the main tag, you can use the "-p" option.
E.g: If you want to use this tags: tag1 tag2 tag3 tag4 tag5
tag1 will be the "main tag".
You can run steemcli like this:
steemcli ... -p "tag1" --tags "tag2,tag3,tag4" ...
By default, the value associed to "-p" is "steembin", that's why if don't use this parameter you'll get "steembin" as a main tag.
In other words, the value of "-p" is concatenated with your original tags to create the tags of your post.
Hopefully it helps.