What I think he's trying to say is that spammers will use your email address as a falsified "from" field because github is a treasure-trove of real looking emai

What I think he's trying to say is that spammers will use your email address as a falsified "from" field because github is a treasure-trove of real looking emails. That doesn't impact you at all if your email's domain happens to be one that does SPF correctly (which every major provider does do) you should be fine because those false emails will be bounced prior to them being able to impact spam score. If you have a really poorly configured email server, it's very possible someone could make you have a terrible time with spam filters by sending spam from "you". Of course, this can happen just as easily with or without Github in the picture typically.