I'm having a hard time understanding your point.
The flow should be coming down through the nozzle at a relatively high speed. It's going to hit the (dimpled) baseplate, wether the pin is there or not. The pin will have little to no effect on the flow, but it might add to the heat being spread, which is always good.
In jet inpingement, it is known that there is a deadspot (i.e. no flow) in the center of the affected area, at the baseplate. By having a pin, you take maximum advantage of jet inpingement, by bypassing that deadspot.
The only important thing to remember is that the pin should be in the shape of a sharp point, otherwise the flow will break up at the top of the pin.
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