This is a non-starter. Paladins don't get their powers revoked in D&D 4e, nor are they granted by a god to begin with. If you have your PHB1 handy, turn it open to the Paladin class description and take a look at the paragraph in the top-left of the second page.
In short, Paladins receive their powers through training, an initiation rite, their boundless faith, or so on. Once the Paladin has started down the path of being a Paladin, their powers are their own and are theirs to keep. They are not granted daily by a god, but simply the Paladin's own, as an expression and manifestation of their faith. They cannot be revoked any more than a Sorcerer can be robbed of their spells or a Rogue can be robbed of their ability to smuggle knives into peoples' faces. (For the record, the same applies for Clerics and other divine classes.)
This is a pretty significant departure from previous editions. Another significant departure is that the Gods are distant and mysterious, and generally not concerned with interacting with mortals. Mechanically, the Gods are almost entirely irrelevant.
What should happen instead?
Instead, your dwarf would have his divine order turn their back on him. Pelor may do so, but it's highly unlikely he or his order had much contact with Pelor or his servants to begin with. The dwarf would still have his powers, because D&D 4e doesn't have any concept of power-revocation. He may simply be unable or unwilling to use them, possibly out of shame, or out of threats by his order. How you handle that is up to you.
Is there any reason Pelor shouldn't revoke his powers?
Yes: You'd set a precedent that 4e works the way 3.5e did where it does not and should not, and send two clear messages. First, that divine classes should constrain their actions based on alignment under fear of loss of all power, and second, that alignment is mechanically significant.
Neither of these things are the case otherwise, and D&D 4e is designed based on the idea they aren't the case. Classes are designed to be equal and balanced at all levels, and the alignment system is mechanically so insignificant you could remove it and affect almost nothing. 4e doesn't share 3.5e's philosophy of major catastrophic character damage being an OK thing - destruction of levels, attribute scores or unique equipment generally just doesn't happen, and nor does loss of class features.
Overall, in 4e I would strongly advise staying with D&D 4e's philosophy of Divine classes not being god-fuelled or under threat of losing their powers. The consequences suggested - a character's order hunting them down, among other things - are more appropriate for 4th edition, and push the story forward in accordance with its heroic themes.