RC Snubber Circuit on Reversing Motor
An RC snubber is perfectly linear, you only have resistors and non-polarized (usually film or ceramic) capacitors. So it work exactly in the same way both in the forward and in the reverse direction.
The other common encountered snubber (the RCD) is not, since it has a diode: like this, it's used for dampening inductive switches but it's optimized since the spike is only in one direction. That won't work in a bidirectional brushed motor.