When Rosalind and Celia enter the forest of Arden in As You Like It, they never go to find Rosalind's father, Celia's uncle, as Celia had suggested when she conceived their plan. Instead, they immediately buy a cottage and a flock of sheep and hire the old shepherd Corin and set up private living arrangements. It is because of this independence, outside the protective shadow of a man's presence, that Rosalind remains in disguise as Ganymede because two women alone would still be in danger.
When in Act 3, Scene 2, Rosalind/Ganymede and Celia/Aliena eavesdrop on Orlando talking to Jaques the melancholy about Orlando's love of Rosalind, Rosalind hatches her scheme to approach Orlando, dressed as she is as Ganymede, and pretend to be a commoner ("lackey") and in that character ("habit") act like a crafty fellow ("knave") and play a mean trick on him. This Ganymede character trait matches with Rosalind's earlier character traits demonstrated when she was eager to see the wrestling match because of the serious injuries to Charles' first three wrestling challengers, while Celia and Touchstone protested against it.
The verbal repartee (swift witty replies) that Ganymede engages in at Orlando's expense are in keeping with the repartee that Rosalind habitually engages in with both Celia and Touchstone. Also, although Rosalind was stunned and numbed after being banished from court by Frederick--even though she ardently spoke up in her defense as well as in defense of her father--which left Celia to devise their escape plan, Rosalind did regain composure enough to modify the plan by the addition of disguising herself as a male who carries an ax and a spear. Ganymede's later address to Silvius, the young shepherd in love with Phebe, and to Phebe, is in keeping with the assertiveness Rosalind has shown all along regarding the wrestling match, standing up for herself and her father, taking on a disguise that assertively includes weapons of the hunt and defense.
Rosalind's behavior while disguised as Ganymede stems from the same behavior she demonstrated as Rosalind and comes from the same core values of integrity, truth and virtuousness. The one thing Rosalind does as Ganymede that she didn't previously do as Rosalind (perhaps their was no opportunity for it) is to contradict Celia: when Celia pities Silvius in 4.3 Rosalind says, "Do you pity him? no, he deserves no pity."
Rosalind's treatment of Silvius while disguised as Ganymede is in accord with her other behavior while in her rightful identity as Rosalind. One role Rosalind has in As You Like It, as the symbolic representative of Duke Senior, is reestablish harmony and the authentic ruling power that was overthrown by Duke Frederick. Thus while she was under submissive restraints at court as Rosalind, the restraints are removed in the forest because she is no longer the submissive guest in the home of the man who rob her father's throne and banished him to exile: Roalind can assert her rightful role to rule as the princess daughter of the ruling Duke.