I believe they are the real deal. If they are fakes, the guy has plastered fake Zegna tags in the suit (these are not simply "Tessuto Zegna" tags). I emailed with this guy once and I think they are the real deal. However, I don't know whether the Swiss made suits are as good as the Italian ones, but I imagine they are. You might want to ask for details re: the pants. The Zegnas intended for the Italian market often has uber-narrow pants. Who knows what market these were intended for.
I've owned Swiss-made and Italian-made E Zegna suits. The Italian ones tend to be priced higher, but they were equally well-made and I wouldn't be able to tell the difference. So, I wouldn't let the "Switzerland" label dissuade you from buying. I don't have any experience with that seller, but the suits look fine. The prices aren't that great though.