The unambiguously correct term they could have used if they were truly trying to tout their product in good faith is "wider". Calling it "bigger" when only one dimension is bigger and the other dimension and the area and resolution are lower is stretching the limits of good-faith. It looks like a deliberate use of an ambiguity to imply something untrue, and no, the marketing people don't deserve the benefit of the doubt that they might not have understood the difference between diagonal measurement and area measurement.