It is the duty of all members regardless of rank to correct poor military dress. It is done with respect for rank but yes a Pte can correct superior rank but he does so from a subordinate position.
I'd like to see the ref for that. However, aside from Unit and RSM'isms...
CFP 265, Chapter 1:
9. High standards of dress, deportment, and grooming are universally recognized as marks of a well-trained, disciplined and professional force. Commanders shall maintain the standards at all times
to reinforce these characteristics for peace or war.
10. Officers cannot delegate their leadership responsibilities. They are assisted by warrant and non-commissioned officers
(Sgt, MCpl and Cpl), who control standards and compliance by all their subordinates.
QR & O, Vol 1, Chap 5, Art 5.01
5.01- GENERAL RESPONSIBILITIES OF NON-COMMISSIONED MEMBERS
A non-commissioned member shall:
a. become acquainted with, observe and enforce i. the National Defence Act,
ii.the Security of Information Act, (5 June 2008)
iv.all other regulations, rules, orders and instructions that pertain to the performance of the member's duties;
(See articles 1.12 - Regulations and Orders to be Available to Members and 4.26 - Circulation of Regulations, Orders, Instructions, Correspondence and Publications.)
b.afford to all persons employed in the public service such assistance in the performance of their duties as is practical;
c.promote the welfare, efficiency and good discipline of all who are subordinate to the member;
d.ensure the proper care and maintenance and prevent the waste of all public and non-public property within the member's control; and
e.report to the proper authority any infringement of the pertinent statutes, regulations, rules, orders and instructions governing the conduct of any person subject to the Code of Service Discipline
That is what the book says, and that is the same book that could be used against a Pte who decided to take it upon themselves to 'sort out' a superior if they found themselves facing admin or disciplinary measures for their actions.