The anti-aliasing is happening at the drawing stage in the client apps – normally it’s desirable to draw upscaled content with anti-aliasing.
For presentation on a > 10×10 display, I would do the resizing yourself prior to sending it to Syphon so you can control the process. For what it’s worth, you could try filing a feature request for MadMapper to be able to skip anti-aliasing.
If you’re presenting it on a 10×10 device, make sure your output resolution in MadMapper is set to 10×10.
For recording, if you record at > 10×10 then it is likely to be anti-aliased during recording. If you record at 10×10 then you should get a faithful copy of the original – but of course if you play it back above its original resolution then the player is likely to anti-alias it for display.