I think you're wording is a little misleading. We know that in the time frame of Morgan's disappearance that JM had his taxi license, however, we don't know for certain that he was driving a taxi on that particular night. Just a clarification, so that people don't assume that it has been confirmed that JM was in fact driving a taxi that night.
I had not heard/read anything about the Bass family being on a cruise during the time of Morgan's disappearance - do you remember where you heard/read that info? I've not been able to find anything with a Google search.
Killers will sometimes return to the scene of their crimes for psychological or physiological release/comfort. The reminder of their crimes is euphoric - it can become an obsession to recreate that feeling, much like a drug addict.
Some link was found between MH and Hannah's case. Le hasn't said what it is. Hints that it involves DNA, but nothing to quore for sure No idea whether JM was driving a taxi that night or what he was doing at all that night, and no word that anyone can pinpoint that Might be difficult I d have tough time alibiing anyone that night even my self. Maybe cab records were kept, If he were driving a cab actively that time, there'd be some chance one could see if he was "on " that night, had a cab. But reports that MH was hitchhiking are out there too. JM or anyone could have been just cruising along and saw her and picked her up. With so much time in between, forensic evidence, DNA evidence will be very important in that case. No charges yet.
Doesn't matter if Bass family was on a cruise or on the farm. It's a huge farm and where MH;s body was found, it 's easy to see that it was highly unlikely that anyone would have noticed someone dumping it there. No one reported a car coming near the place, or anyone dumping anything. JM nor anyone was in the picture for MH.