Crimson Longinus
Legend
Right, they just use 'psychic powers' which totally are not just another name for spells! Make a fluff sidebar that psions use 'psychic powers' which for rules purposes are represented by spells. Done.People who want psionics are consistent about one thing: psionic powers aren't spells. If the character casts spells, they're not a psion.
Therefore, the character in the OP isn't a psion. It's a psychic-themed spellcaster.
Now, there's no actual consensus on what psionics are - just that they are not spells. So I understand WotC's problem here - they really ought to just pick an mechanic and run with that, surveys be damned. If the class doesn't suck (and doesn't cast spells) people will get on board. Every other ask is just a detail.