Its your game, your universe.
So if you want to allow these characters to do the research and come up with a cure, then this is perfectly acceptable to do.
Thing is, the flaw does not actually exist. Odan simply refused the transporter on medical grounds. But this was simply to protect the secret of his symbiote.
So if its a game during the early TNG era and your Trill is joined then she would have a vested interest in not completing the 'research'. If however its after the exposure of the secret or she's an unjoined you can simply ignore the Transporter 'allergy', and instead change it for extreme sensitivity to insect bites (which does cause the trill problems apparently).
Of course if you want to keep the transporter intolerance for flavour, and still allow the crew to find a cure, then work out how long it will take to complete the research, and presto, the week before you have a player-led plot with a transporter accident episode, when they test the research (I am sure that as the lead scietist and a trill, your player will be up for being the first test subject)...
DanG/Darth Gurden
The Voice of Reason and Sith Lord
“Putting the FUNK! back into Dysfunctional!”
Coming soon. The USS Ganymede NCC-80107
"Ad astrae per scientia" (To the stars through knowledge)