They should definitely create a new clearnet website since the old one no longer works, but there shouldn't be a link to the onion website. Instead they should link to this ANN thread and instruct users to check the OP where the correct onion link is posted. Or at least ask customers to verify that the posted onion link on the clearnet site is the same as the one that appears in the Bitcoin ANN. Just in case the clearnet version gets hacked and someone posts a link to a fake mixer. Someone could of course post a link to the wrong Bitcointalk thread or a completely different source, but I think the potential damages are smaller by linking to the ANN thread as well.
I don't think relying on a third-party website (Bitcointalk) as a primary source for the real URL is a good idea, and I'm not sure how many people are going to verify it. But I've seen confused users who weren't sure what the real URL is.
I think the reasoning would be that this site is harder to interrupt/ddos due to cloudflare and I'm not sure liky it'd be that chipmixer could get and host a cloudflare account (eg kyc might be needed and if ddosed too much they might be suspended/charged more).