The pitot tube doesn't exist on the J-20 in Kopp's simulation. There's something screwy with the J-20 if it has a 1 m^2 RCS on a direct heading; because that either means the J-20 is horribly designed or there's effects we don't know about determining its frontal RCS.
It's also possible there's a plasma-stealth system being used on the J-20's radome. A key problem with stealth radomes is that the AESA electronics are inherently unstealthy, and for the radar to work, the AESA would have to be exposed. Using RAM on the radome results in a reduction in AESA sensitivity because the returning radar signal gets absorbed by the RAM instead of the AESA. A plasma-stealth system, limited to the J-20's AESA, can work extremely well, since there's already a space placed for containment, it's on the inside of the plane, and there's not a lot of space that needs to be blocked by a plasma.