Indeed, I would argue it goes one step further. Not only is the testimony itself not available, but evidence generated in reliance on that testimony is not available either. More than that, evidence generated elsewhere, which is not appreciated for its significance without reliance on that testimony, is itself unavailable. But these are all points or evidentiary arguments one would make in court on the occasion of being presented with testimony before a committee, and the courts would draw their conclusion.
I'm reminded, of course, that there's always the possibility that the House could waive its privileges in this regard and allow its proceedings to be used, typically for a prosecution for perjury.