@aFFi: Well, they already knew how the kingdom view them.
But to them that doesn't matter, the only person whose view matter to them is the princess.
So even if somehow they think she permitted this plan, all that need to happen for them is that she's there to welcome them 'home' and worry about their injuries and any doubt would immediately go away.
Because she's the only one who treat them as 'normal'.
Heck, the kingdom can shift the 'blame' of this incident to themselves and get these two extra attached to the princess by telling them that the princess was not told of this plan, and once she knew she VERY vehemently disapproved.
After all, she IS still the princess of the kingdom, even if these two hate the king, so long as they're loyal to the princess and she to the kingdom, then in a way the kingdom still own those two.