I'd tell them there is almost no water on venus, that it's like thousands of times dryer than the sahara. Until they have a scientific explanation for an alternative biology that is not water based and can survive in air, it's far more likely phosphine is created by some abiotic process.

I do find it funny because this whole hysteria about life on venus is so silly. There is no reason to assume phosphine is being created by a completely alien, non water based biology. But they want to believe and/or sell clicks.