IANAL, but disagree. In the context of business relationships, tortious interference is "intentionally acting to prevent someone from successfully establishing or maintaining business relationships with others".
GRJ is not preventing anyone from maintaining a business relationship with Google.
That Google might -choose- to end a business relationship is on them, but they weren't prevented from having a relationship with their YouTube 'customer', or vice versa.
It's more complex. If my app causes someone else to violate ToS, it's very much on realm of the types of things which lead to expensive litigations as I've seen in related domains.
GRJ is not preventing anyone from maintaining a business relationship with Google.
That Google might -choose- to end a business relationship is on them, but they weren't prevented from having a relationship with their YouTube 'customer', or vice versa.