If it doesn’t have eggs, it’s not Mayo, just like corn syrup and red dye isn’t ketchup. Margarine isn’t butter. Call it something else.
A typical dodge in such a situation is to label the product “Mayonnaise style dressing.” Don’t know what JM uses as a name.
Because Mayonnaise is and has been defined as:
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=169.140
Salad Dressing:
http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm?fr=169.150
It’s been a long time since I was in the business but I believe that a product like this would be called a sandwich spread, which is somewhat ill defined.