The claims made here are tied to the fact that English is more or less the primary language of international business. Its well known that people who learn secondary languages tend to know the "rules" around the language and tend to be more specific when using secondary languages.
Its pretty weird for the article to conflate using slang/abbreviations/language tied to cultural norms from a primary speaker as being unable to communicate.
Other languages have built in cultural connotations that pretty much only matter within their specific culture that doesn't really make sense outside of it.
Sure when knowingly speaking to a multicultural audience, its probably for the best to not use idioms and such, but the failures of communication is not tied to the fact that English is being used.