P.S. The Glowing Guardian was always intended as a stern bastard, difficult to please and horribly judgmental.
If you approach him naively, he certainly plays this way. Once you figure him out, though, you realize that his religion is all about one-night stands (sorry for the crude metaphor). All his boons are one-shot deals, and the only penalty he ever gives you is booting you out of his religion. Yeah...
I already got what I wanted, sucker
Two full heals (or a full heal and a death protection) is way
better than most gods will ever offer if you begin worship after level 6, and it's effectively free. All you need to do is not
piss him off in the short period between joining his religion and cashing in on your boon. He will almost always offer more than 50 starting piety if you join him late enough (usually during the boss fight) and you'll almost never be able to save up for a second boon anyways.
His restriction on APHEELSIK and BLUDTUPOWA is largely academic. Maximizing your starting piety with glowing guardian means beginning your worship after you've completed exploration... by which time the usefulness of these glyphs has expired and there's nothing left to do but convert them. His love of HALPMEH and CYDSTEPP is similarly irrelevant; either convert them before joining or convert them after cashing out your piety.
Those are some really vivid concepts.
I grew up in the days when video games left much
to the imagination, and enjoy just sitting back and imagining these things.