Would a Minotaur Reckoner prevent units from activating Reaver's Row?

No, a Minotaur Reckoner would not prevent units from activating the ability of Reaver's Row.

Here is the breakdown of why:

1. The Ability: Reaver's Row has a triggered ability: "When you defend here, you may move a friendly unit here to base."
2. The Restriction: Minotaur Reckoner has a passive ability: "Units can't move to base."
3. The Interaction: While Minotaur Reckoner prevents units from moving to the base, it does not prevent the activation or triggering of abilities that attempt to do so.
   • When you defend at Reaver's Row, the trigger goes on the chain.
   • When that trigger resolves, you may choose to move a unit to the base.
   • If a Minotaur Reckoner is on the board, the instruction to "move a unit to base" simply cannot be followed because of the restriction. According to Rule 356.3.e.6, "Instructions that can't be followed, either because of illegal targets or other circumstances, are ignored."

Therefore, the ability still triggers and resolves, but the move itself will fail to occur. You can still trigger the ability (for example, to satisfy other card effects that care about the ability being used), but the unit will remain at the battlefield.