Guardian with Plasma Burn would be just a significantly worse Radiant, instead of a somewhat worse Radiant.
It also costs 40 dp so yeah, being a worse radiant isn't exactly a bad goal to hit.
it costs 40 dp, cause it needs to make up for Derelicts being generally bad, but also let them deploy. If Guardian costed more, it would eat too much DP and cause a large fleet of Derelicts to simply not deploy until they are destroyed, which would in turn make Derelicts useless. Cause their only job is to be a distraction, because they lack kill potential.
(you can see this happen if you have High Tech Tri-Tachyon fleets even with DP advantage. Or Luddic Church. Deploying Astrals, Paragons, Invicti will drain their DP and then make their escorts go to waste, because they will either die too early to escort or deploy only after core ships were destroyed. Making them useless)
In order to make a Guardian abductable imo, I think it would need to have less op, removed Advanced Targeting Core. Keep its speed, but maybe change Hybrid Slots at the front to Ballistic (or maybe energy, it would be the only Midline ship in the game focused around roaming with Large Energy). Give it 1.4 shields. And obviously remove its Missile Autoforge.
Its DP should also be increased to 50-60 then. But if that was done, then other Derelicts would need buffs. A thorough increase of armour, durability, flux stats. And then a change of how AI deploys ships to prevent it from overspending DP on capitals causing it to not be able to utilise escorts would solve this... But eh, theoretically.