I was running ClamAV on my Linux the other day and it spat a bunch of detections for an extension in Chrome, identified by this ID - cjpalhdlnbpafiamejdnhcphjbkeiagm. This comes from the filter at Malware Patrol. It might be a good idea to add another entry to the False Positive page.
I also tried to contact them, but their contact form is really not helpful. Maybe someone else has better luck.
I was also wondering if uBlock could be a vector for malware - meaning malware having integrated itself in my local uBlock after installation? I can't tell if uBlock is verified by Chrome in some way.