There is tension between "free to distribute" (which implies you can get it without paying), as well as "free to modify" (which implies you can build it yourself from source) and "the need to ensure that development continues".
But it is only a tension, not a contradiction. Anyone can get Ardour without paying, yet it raises $200k+ per year to help ensure that development continues.
I wonder if it applies to the kind of software that is more complete like anything with a UI etc. If I get the final result the tests don't mean much to me.
In fact, what Bruce is proposing is a "source under glass" license. Look, but don't touch. Pay to play. Microsoft offers some companies access to the Microsoft Windows source under that kind of license. Is it open source? No.