Hello Ben
If you make a drop rule for traffic coming to this port then it will stop showing in the report (but this will not really hide it). Like we have a FWSM sending level 7 syslogs to the MARS. We says a lot of 'sessions' were related to SNMP, Proxy 8080. So we just made a drop rule for both and this greatly reduced the load on our MARS, reducing I think about 2 million events per day.
Also just to 'hide', you can most probably edit the Query, click on destination port and add "NOT EQUAL" Port 1720. You can also filter by source IP/Destination (for example exclude traffic directed/sourced from the IPT server).
Regards
Farrukh