He did not say it causes aliasing, he said it is inviting aliasing.
More resolution is going to be fine if the pixels are filtered well. If they aren't, that could certainly invite aliasing. Pixel filtering, especially in a scenario like this, is going to have a wide spectrum of techniques that can work to varying degrees, with trade offs of quality and speed.
A pixel filter that takes into account the highly nonregular shape of the projected screen pixels and the warped projected video pixels in the source at the same time would be quite an interesting task.
More resolution is going to be fine if the pixels are filtered well. If they aren't, that could certainly invite aliasing. Pixel filtering, especially in a scenario like this, is going to have a wide spectrum of techniques that can work to varying degrees, with trade offs of quality and speed.