The argument that the omission of the word "can" in the PP feature makes no difference to the application of precision. However, if this is the case, if it supposed to work exactly like all the other powers and feats that say "you can score a critical hit on X", WHY is there a need for different wording?
Because it's a different rules template. The other abilities are all 'You can score a critical hit on a natural x-20'. This ability isn't an ability of that exact type. It doesn't describe a range between x and 20 wherein criticals are now allowed to occur, but instead says a different sort of situation that allows a critical to occur.
So, of course the wording is going to be different.
The first case is 'You can do blah when you roll blah'. The second is 'Whenever blah, do blah if blah except blah.'
The other question is, does the word 'can' refer to the potential to crit, or does it simply mean 'Hey buddy. You see that rule over there? You know how it says you can't do something? Well I'm saying you can.'
Is it mentioning potentiality, or is it simply giving you permission to crit?
And the language isn't so formal in D&D books that a 'may' vs 'can' argument comes up.
Especially considering that 'may' can also be used in both senses.
Obviously there was some rules oversight involved. Either precision was overlooked and the intent is that doubles equals an critical hit regardless of whether the roll would have hit, or the wording on the multitude of other examples was overlooked.
Or those examples have subtle differences that mean that the rules templating for them are not the same as the rules templating for this, new, unique ability. There's other differences in how the ability is written as well. Does the ability function differently because it starts with the word 'Whenever'?
The only other instance of a critical hit that isn't roll-range based -was- Tempuscheese, but the situation involved in that was 'You hit' and so it isn't necessarily the same deal.
Personally I think it more likely that precision was overlooked and the intent of the power is that "you score a critical hit" is meant to be different than "you CAN score a critical hit".
The rules templating is totally different between the two, the word can is a very minor difference, given that the -order- and -layout- of the two templates are not even close to similiar. The first is a mention of a single condition, the third is a damn pretzel of triple conditionality. Expecting it to read the same is an exercise in failed expectations.