Notice how the masthead at the top looks very similar- Tritans do not have a problem with reds or greens. Some with a very mild Tritanomalous defect would see the site almost the same as a colour normal.
This is a simulation of the most severe form of a blue defect, some with a very mild defect would see the site almost the same as a colour normal.
Ishihara Colour Vision testing simulation
Notice in the above two plates that the Tritan has no problem seeing the numbers on the plates- these plates were designed to, and are only capable of detecting red/green defects.
The plates don’t look correct to a colour normal, but the numbers are still visible.
These are only simulations! Your monitor calibration, room lighting and own colour vision will affect what you see, but it does give a fair simulation.