[a3n]

For the same reason that my email client occasionally tells me "this may be a scam," even though sometimes it's not and I act accordingly. Based on whatever criteria it's using, the data received has a somewhat higher chance of being illegitimate.

We as (technical) humans can recognize (hence this discussion) that the use of this uncommon G is meant to mislead you into thinking you're going to Google, when in fact you're going to Hell. I'd like to be warned of that possibility.

In this case, the extremely oversimplified algorithm might be "does the domain, as filtered down to canonical characters, represent one of the top five destination domains, yet go somewhere else if not canonicalized?"