  We evaluate the usefulness of holographic stabilizer codes for practical
purposes by studying their allowed sets of fault-tolerantly implementable
gates. We treat them as subsystem codes and show that the set of transversally
implementable logical operations is contained in the Clifford group for
sufficiently localized logical subsystems. As well as proving this concretely
for several specific codes, we argue that this restriction naturally arises in
any stabilizer subsystem code that comes close to capturing certain properties
of holography. We extend these results to approximate encodings,
locality-preserving gates, certain codes whose logical algebras have
non-trivial centers, and discuss cases where restrictions can be made to other
levels of the Clifford hierarchy. A few auxiliary results may also be of
interest, including a general definition of entanglement wedge map for any
subsystem code, and a thorough classification of different correctability
properties for regions in a subsystem code.
