Many research institutions and funders have recently stated their commitment to actively support and promote 'Equality, Diversity and Inclusion' (EDI) in various aspects of health research including Patient and Public Involvement (PPI). However, translating this commitment into specific research projects presents significant challenges that existing approaches, practical guidelines and initiatives have not adequately addressed. In this paper, we explore how the lack of clear justifications for the EDI commitment in existing guidelines inadvertently complicates the work of those involved with PPI and we stress the need for conceptual clarity for any EDI effort to yield meaningful results. Our focus centres on the first principle of the EDI discourse, 'equality', particularly in the form of 'equality of opportunity' as outlined in current guidance provided by the National Institute of Health Research in the United Kingdom. We examine challenges related to justifying and implementing a general, unspecified commitment to equality of opportunity and explain that this reflects a lack of consensus regarding the moral value of PPI in research -- a profound problem that remains unaddressed. We then discuss how the presence of several opposing moral perspectives on PPI, makes determining the most appropriate way of addressing barriers to involvement complex and controversial, raising ethical implications for the work of health researchers, PPI specialists and coordinators. Finally we make suggestions on how future research can enrich the concept of 'equality of opportunity' in PPI and improve practice. While our primary focus is on the NIHR, a strong advocate of PPI in research, this analysis will point to normative and ethical considerations that may be relevant to other research institutions and funding organisations aiming to promote equality of opportunity in their public and patient involvement strategies.