Also, having explained by example, finish with "quod erat demonstrandum"

It’s fine to have it as a normal word, it might even be one! Hehe it is to me at least :)

However, I believe OP is right, it’s un…grammatical? -parasable? in the headline? There’s no…referent?

More plain spoken :) - there’s nothing indicating what lead to the thus. I.e. “it’s raining thus I brought my umbrella”, we’re missing the “It’s raining” part