A breach of the Terms and Services that all publishers are required to abide by, to have a relationship with Google and/or Apple. They have a list of security provisions and list of things you can and cannot do.
Nothing in the article implies that Variston has any relationship with Google and/or Apple or wants one. T&C is not the law - it may be a condition of Variston being able to publish apps on Google Play and Apple Store, but Variston definitely has (and should have) the right to refuse that T&C and not publish any apps, you can't unilaterally impose contracts on others.
> On what grounds?
A breach of the Terms and Services that all publishers are required to abide by, to have a relationship with Google and/or Apple. They have a list of security provisions and list of things you can and cannot do.