A few paragraphs down, they say:

“Unfortunately, one of the three trustees has irretrievably lost their private key, an honest but unfortunate human mistake, and therefore cannot compute their decryption share. As a result, Helios is unable to complete the decryption process, and it is technically impossible for us to obtain or verify the final outcome of this election.”

⇒ that first paragraph is badly worded, but they’re not hiding facts.

I also think “3 out of 3” is not a good idea, as it allows any single key holder to prevent election outcomes that they don’t like (something that may have happened here, too. I don’t think cryptography experts often lose such keys by accident)