I mean, they PROBABLY shouldn't talk about certain secret things in public, but that's SO inconvenient to write around--I mean, for them, so they'll probably due it anyway.
But yeah, Susan didn't want to start talking about how Zeus spilled the beans about immortals in public when there could be an invisible immortal hanging around.
Granted, maybe she could have swung her arms around wildly to see if she hit anything? That might be an option now? It's not a great one, but it MIGHT be on the table?
Edward Knew! A Bit!
In order to confirm that Susan was, at a minimum, partly correct, and for them to KNOW that Susan was correct, Edward needed to know about some of this already.
Which was fine, because I LIKE him and his associates not hearing about this for the first time from Susan. It's their business to know this stuff.
I also like Susan being smart, but not as absurdly observant as Edward thinks she is.
Context and expectations make a huge difference in how we perceive information.
In this case, Susan perceived those comments as personal messages for her. She did so by coincidence, and for entirely the wrong reason, but she did.
Assuming Zeus did leave those messages, his approach might have completely failed if not for that coincidence.
Which I like, because life is like that sometimes.
Heck, writing this comic is like that sometimes. For everything I've planned out well in advance, there's something that looks planned that I instead fell over backwards into by accident.
Tedd is overdue for a haircut. That's what's going on there.
Tedd looks sort of good like this, however, and is contemplating various hairstyles, so maybe Tedd's NOT overdue for a haircut.