Yes, a referral to urology for possible cancer should be triggered by a PSA of 3.1 or more so his reading of 120 means that he almost certainly has cancer. What they won't be able to say yet is whether it has spread to other parts of his body - on Tuesday, they may do an MRI scan or a bone scan, or they may just do another DRE (finger up the bum) and book him in for scans at a future date. Usually, they would book a biopsy for a couple of weeks after the MRI scan but if the scans show that there is already significant spread, they sometimes don't bother with the biopsy.
As I said, you are unlikely to get a confirmed diagnosis on Tuesday but if they are almost certain that it has spread, they may start him on hormone treatment immediately just to stop it in its tracks.
Although I said that anything over 3.1 is a concern, the highest reading we have ever had on here was 13,000 and our urologist says he once had a patient with a PSA of 160,000 so 120 isn't catastrophic or immediately life threatening.