An outtake quote doesn't provide a reasoned arguments—can be is a tell, along with the undefined functionality.
All proprietary solutions claim that they are more cost effective than their competitors, commercial or open source. It could hardly be otherwise. Successful proprietary solutions also take care to bait the hook with a killer use case with an attractive price point.
But enterprises with institutional memory have seen this series before it went into syndication. The true cost of a platform is not the hardware or the software, but the wetware. The costs of training and skills maintenance across the lifecycle is what determines the relative value of a software solution.
An even more important consideration is cognitive capture. A closed platform only allows the expression of thought in its language. If data and analysis require elucidation in a form not available in a platform, that lack deters confronting the situation.
Back in the days when business intelligence meant poring over six-inch stacks of greenbar, eye candy wasn't an issue. Managers sucked it up and did the hard eyeballing and pencil graphing. Visicalc evolved into Excel and displaced the skull sweat with cartoon charts at the expense of both data processing error and dumbing down the assessment of data and analysis.
The teleology of both Tableau and Shiny, without care, is not analysis but persuasion that everything is coming up roses.
The choice between the two is primarily a matter of whether to be stuck with a toolset that is useful only for pitching a sale or one that may, with effort, also be used to get a conviction.