Sylvester didn't know how important the Princess was to her brother or if she had received permission from her brother, the King, to seek them and explain things. But he decided to keep her close if things came to a point where he had to force the King.
As for the Princess, he held no repulsive thoughts since she did not lie the whole time. She did heal Sir Dolorem in the past and seemed sincere about helping him heal now. But on a side note, Sylvester felt she wanted to ensure Sir Dolorem lives to save her kingdom from peril.
So, he allowed her to see Sir Dolorem while the blockade cleared up. But, as their boat started to move ahead, the guards of the Princess also followed behind. But he didn't mind, as they wouldn't be allowed inside the Holy Land anyway.
"Knights pledged to my family did this?" Princess Isabella sat beside Sir Dolorem's body in shock. Seeing how badly the man was injured had shaken her belief towards her brother too.