Apache Beam _can be_ but this person is talking about using it inside of Google (e.g. as the Dataflow API) and with a Google service. I think the comparison is on the money. That being said I think the best way forward would be both google cloud support & a JIRA ticket.

Although, to a degree, I think the authors complaint about Google's mentality towards open source is on the money, a lot of the OSS work is understaffed with the theory that the community will pick up the slack, even when the primary users of the OSS project would be Google customers.

(Full disclosure: I work on Apache Spark for my day job, have previously worked on Apache Beam for my day job, and have friends who work on Bigquery so my world view is maybe skewed).