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R2 is absolutely needed to limit the current through the base of Q2. The base-emitter junction of a bipolar transistor looks like a forward biased diode, thus the current is limited only by the external resistance if you apply a voltage above the forward bias voltage (about 0.6V) of the junction.
With R2 in the circuit, the 12V will not damage the PIC input, even if Q2 fails.
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