As far as I know, Localbitcoins does not even allow trading on their site if the transacting parties are in Germany.
http://bit.ly/2kWvw3fOperations involving Localbitcoins trades in Germany ceased in 2014. I'm not sure if anything has changed since then.
Since your friend wants to deal in person and pay with cash, then the above is irrelevant but still something I wanted to mention as a point of interest.
I'm not sure if you will find anyone willing to travel to Loerrach to trade a few coins. Your friend might find offers involving a SEPA transfer or Sofortueberweisung.
He might want to consider buying from BitPanda in Austria:
https://www.bitpanda.com/Or taking the train to Basel and buying coins at the ATM:
https://www.bitcoinsuisse.ch/atm-network/Viel Glueck!
Yes, the atm option is actually useful for him. But does it need bank payment(debit, credit cards etc.) or payment in cash is possible with it?
And about your first revelation, I actually did a search on localbitcoins, looking for sellers in Germany that do accept in person selling and payment in cash, and I did found a couple of options in Germany too.
Should I restrain him from contacting them?