Can the MBA provided by Repel Charge be made at reach?

Question

A player in my group is building a PC with a reach weapon

With a reach weapon, a creature can make melee attacks against enemies that are 2 squares away from it as well as adjacent enemies. Even so, the wielder can make opportunity attacks only against enemies adjacent to it and can flank only enemies adjacent to it.

and he wants to take the Repel Charge feat:

Whenever an enemy makes a charge attack against you, you can make a melee basic attack against that enemy as an opportunity action.

His question is: Can the MBA provided by Repel Charge be made at reach, before the charging target is adjacent to the PC making the attack?

Relevant rulings may include that melee basic attacks have a reach of weapon, and that:

Just like an immediate interrupt, an opportunity action interrupts its trigger, taking place before the trigger finishes.

As noted above, the restriction on opportunity attacks with reach weapons applies to the subset opportunity attacks, rather than the larger set opportunity actions (which is what the Repel Charge attack is). Otherwise this would be trivial.

Answer 1

As long as the enemy is a valid target of the MBA you can.

The feat Repel Charge does not have an adjacency requirement so the character repelling the charge merely needs melee range on the person charging them. This is not an Opportunity Attack which does require adjacency, it's a set Opportunity Action. It's part of the same super set (Opportunity Actions) as the Opportunity Attack, but is a completely different action.

Note, the wording here is pretty specific, your opportunity action interrupts the attack portion of the charge, so he gets to move as close to you as he wants to before you get to hit him. Reach only comes into play when the monster also has reach.