How does ことはあっても connect this otherwise 2 part sentence into one?


> **獄長** ：「な～に、馴れればここでの生活も満更ではないぞ。どうせ **シャバにいたところで他人様の迷惑になることはあっても役には立たない**
> ボンクラどもなんだからよ」
>
> **Warden** : Once you're used to it, life here isn't too bad. Here you
> trouble only useless fools....

I would like to know a more literal version of the bold part. My guess is
either he is speaking or directly about the prisoners in question:

  * "Either way, on the outside you were all a nuisance to others, however, in here you are only fools."

Or maybe:

  * "In the outside world, there may be others who are annoyed but they are all blockheads."




Almost everything before ボンクラ is a long relative clause that modifies ボンクラ. So
the basic structure of the sentence is:

> どうせ _< long description here>_ ボンクラどもなんだからよ。  
>  After all, you (prisoners) are idiots who are _< long description here>_.

The long relative clause contains several clauses:

> シャバにいたところで  
>  even outside the prison, (lit. "Even if you are in the free world,")
>
> [他人様の迷惑になること] **は** あっても  
>  who may trouble others but  
>  (look up the ～ことがある construction in case you did not know it)
>
> (他人様の)役に **は** 立たない  
>  who are not of help (to others)

Notice the two contrastive-は's (bold). Therefore a translation would be:

> どうせシャバにいたところで他人様の迷惑になることはあっても役には立たないボンクラどもなんだからよ。
>
> After all, you guys are idiots who would only be troublesome but never
> helpful to others even if you were outside the prison.




Almost everything before ボンクラ is a long relative clause that modifies ボンクラ. So
the basic structure of the sentence is:

> どうせ _< long description here>_ ボンクラどもなんだからよ。  
>  After all, you (prisoners) are idiots who are _< long description here>_.

The long relative clause contains several clauses:

> シャバにいたところで  
>  even outside the prison, (lit. "Even if you are in the free world,")
>
> [他人様の迷惑になること] **は** あっても  
>  who may trouble others but  
>  (look up the ～ことがある construction in case you did not know it)
>
> (他人様の)役に **は** 立たない  
>  who are not of help (to others)

Notice the two contrastive-は's (bold). Therefore a translation would be:

> どうせシャバにいたところで他人様の迷惑になることはあっても役には立たないボンクラどもなんだからよ。
>
> After all, you guys are idiots who would only be troublesome but never
> helpful to others even if you were outside the prison.

