Sufficent connection to Honor allowed one to push through suppression, sufficent connection to Odium should allow one to circumvent it.
How many people at the time are going "Huh, I should really check to see if anyone is glowing with light right now."
And in the next part I explained why it would.
Considering the next mistborn book is named after Atium I have to say otherwise.
We know how Atium interferes with Atium though, just having it won't protect you, you have to be seeing the future in order to be safe, otherwise you have only one path forward.
Unmade do not have a Bondsmith equivelent, and there is no spren for the other lights, the closest to a fifth would be the Dawnshard "known to bind any creature" but that's a dawnshard.
If he thinks something that doesn't use light has changed, why would he think it uses light now?