"Super duper not allowed! Plus you're going to figure it out anyways yourself before very long!"
"So what happens next is that Abadar's people need to put up a Zone of Truth, and guarantee using their own magical detection abilities that nobody messed with that! And then everybody who Keltham currently has feelings for, or who have feelings for him, need to go into that zone and tell Keltham what really happened between them from their own perspective, and what their relationship is currently actually like!"
"Otherwise some people who have important decisions coming up might make those decisions less than totally optimally given their own values! And that would not be in the interests of Asmodeus or Cayden Cailean or Abadar or Keltham."