The phrase "safe cocoon" means a protective and secure environment that keeps someone or something safe. It refers to a place or situation where there is no danger or harm. Full definition
«Being at NHGRI allowed me to leave my borders and safe cocoon behind,» said Rivera. (genome.gov)
Pupae can live for years in their nice safe cocoons waiting for something warm to come close. (professorshouse.com)
To avoid the bullying within a «community of correction», people ultimately depart or become «true believers», and ultimately resort to hatred, name calling, insults, and so forth — which insulates them within a safe cocoon of «pseudo-community» — that is, a community based on «enforcement of sameness». (nakedpastor.com)