"But until the judge rules, the pressure on him NOT to grant discovery will be huge."
Not granting discovery is probably reversible error.
Reversible errror yes, but we've all seen cases where Judge allows all kinds of junk in seemingly to achieve a conviction (or out of laziness or due to pressure), "knowing" an appeals court will sort it out later and do the right thing. The initial conviction is all that makes news. The reversal, if reported, says the accused got off on a technicality.