[impendia]

Yes, they likely scraped the conference web site.

Academia, at least in math, has a tradition of being public. Conferences will advertise at least the list of speakers, and sometimes the full list of attendees. This is widely considered a good thing; people trying to decide whether to go to a conference will want to know who else will be there.

Moreover, the conference organizers have sent out multiple emails to the attendees warning that scammers were targeting them, and emphasizing that there were no third parties legitimately involved.

So I can't and don't fault them.