Confusion regarding the Kir2.1 inward-rectifying potassium channel
Short answer
&quot;Inward rectifying&quot; doesn't mean &quot;only allows inward current&quot;. Current through inward-rectifying channels can be (and often is) entirely outward in physiological settings.
Explanation
For a non-rectifying channel, there is a linear current-voltage relationship. If you plot current through the channel at various holding voltages, you get a straight line.
For inward-rectifying potassium channels, you get less current as you depolarize, like this:

(from Wikipedia)
At negative voltages, the channel is pretty linear and strongly inward (negative). However, at more positive voltages, the linear trend is attenuated.
However, this relationship does not upset the equilibrium potential for a given ion. For a potassium channel, if you have a cell with a potassium reversal potential that is more negative than the membrane potential, you'll still get an outward flow of potassium ions (in the figure, note all the lines above 0, representing voltages more positive than the potassium reversal potential; they're positive/outward even if they're small). What is different for the inward-rectifying channel is that as you depolarize the cell, the current does not increase the way you would expect it to increase for a non-rectifying channel.
For example, for a non-rectifying channel, you'd expect with a potassium reversal of -90mV, the current would be the same magnitude but opposite sign at -120 mV and -60 mV (30 mV above and below reversal). For a inward rectifying channel, you will still have the same change in sign, but the magnitude will be less at -60 mV than at -120 mV.

its inhibition will allow for depolarisation

Any channel permeable to some ion (or combination of ions) will tend to move the voltage towards the reversal potential for that ion/ions. So, as long as potassium reversal is more negative than threshold, all potassium-only conductances are inhibitory, whether they rectify or not.