Hyp's not stating a houserule.
He's saying, to condense it, that a) you're not emulating the 'spells' class feature in order to use spell trigger items, as the half-caster classes (ie paladin and ranger) can activate spell trigger items before they gain the 'spells' class feature, b) the class spell list is neither part of the 'spells' class feature, nor is it a class feature, not being listed under the 'class features' portion of the individual class descriptions, c) your error in reasoning lies in your assumption that the spell list is part of the spells class feature.
Also, according to the SRD UMD DC table, the check to emulate a class feature is 20, not 21.
Just because a class feature references something doesn't mean that it is a class feature.
Otherwise, because the sudden strike and skirmish class feature descriptions reference sneak attack, the rogue would be vastly outclassed, since, as per your logic, because sneak attack is referenced in the class features of both the ninja and the scout, by god, they've got sneak attack, which happens to stack with both sudden strike and skirmish. Yes, that's a boatload of d6's getting picked up that shouldn't be.
Also as a function of his class, a barbarian has his d12 hit die. Now, if Hyp and I are correct in our interpretation of what you are saying, a rogue would be able to emulate that barbarian's d12 HD, granted he'd have to make a DC 20 UMD check every hour or so, but still, that's not something that should be happening.
He's saying, to condense it, that a) you're not emulating the 'spells' class feature in order to use spell trigger items, as the half-caster classes (ie paladin and ranger) can activate spell trigger items before they gain the 'spells' class feature, b) the class spell list is neither part of the 'spells' class feature, nor is it a class feature, not being listed under the 'class features' portion of the individual class descriptions, c) your error in reasoning lies in your assumption that the spell list is part of the spells class feature.
Also, according to the SRD UMD DC table, the check to emulate a class feature is 20, not 21.
Just because a class feature references something doesn't mean that it is a class feature.
Otherwise, because the sudden strike and skirmish class feature descriptions reference sneak attack, the rogue would be vastly outclassed, since, as per your logic, because sneak attack is referenced in the class features of both the ninja and the scout, by god, they've got sneak attack, which happens to stack with both sudden strike and skirmish. Yes, that's a boatload of d6's getting picked up that shouldn't be.
Also as a function of his class, a barbarian has his d12 hit die. Now, if Hyp and I are correct in our interpretation of what you are saying, a rogue would be able to emulate that barbarian's d12 HD, granted he'd have to make a DC 20 UMD check every hour or so, but still, that's not something that should be happening.