I suppose this is grounds enough to enforce a static party rule which enforces the following penalty:

1. Players who left the party finder will not gain any rewards in Eureka for 30 minutes.
2. Players who quit the party cannot enter Eureka AND any duties until the penalty has passed (not that it mattered since there's no reward to be gained anyway)
3. Party leader cannot disband the party until 15 minutes has passed, and likewise cannot be dismiss-voted. Should the party leader quit for any reason (apart from temporary disconnects), s/he'll be barred from Eureka for an hour.

Harsh penalty? Don't think so. They TLDRed and trolled the hand that gave them the free sailing ticket, so they deserved every bit of that punishment.