The author fails to interpret the word 'foreign' correctly and thereby fails in building a convincing main argument.

In this case, 'foreign' is not synonymous with overseas.

A foreign accent is any accent that is foreign to your brain - and obviously there is a multi-dimensional spectrum of 'foreign-ness'.

The author has erred in his judgement, however I can see now why other non-native-English speakers would easily make the same mistake.

The irony of misunderstanding a topic about the importance of communication!