This paper critically examines the notion of 'sheltered' pedagogies for English language teaching in English-dominant contexts. I specifically explore how the increasingly popular Sheltered English Immersion (SEI) model has been interpreted in certain contexts to further monolingual language ideologies. Drawing on critical and poststructural approaches to policy analysis, I ask "who is being sheltered" through SEI -- interrogating the degree to which the model accommodates multilingual learners as compared to 'sheltering' monolingual pedagogies, teachers, students, and policies of the status quo. Ultimately, this framing destabilizes assumptions around "who benefits" from 'sheltered' approaches. I first introduce a theoretical framework to challenge claims of a widespread transcendence of monolingual language ideologies through theoretical advances such as the pluri/multilingual turn. Next, I analyze the socio-historical trajectory of SEI's use within U.S. English-only movements and the language ideologies produced therein. Finally, I provide a specific example of an SEI training mandate in the U.S. state of Massachusetts that demonstrates how monolingual language ideologies can be reinforced through teacher education, even in the absence of specific English-only policies. Beyond SEI classrooms, this analysis has implications for how language hierarchies are maintained across a broad range of educational settings and policies.