There is a long history of division over penal substitution in church history, particularly in the
Way back in 1910 The Split between The CICCU and SCM was precisely over the centrality of penal substitution. The Leaders of SCM at the time didn't deny penal substitution. They merely denied its centrality. IVF (later renamed UCCF) came from those root in
To refuse to allow someone who not only denies the doctrine, but likens it to child abuse is therefore utterly consistent with the roots and foundation of UCCF.