If you insert the key and wiggle the steering wheel as you turn it, I'm sure the key and steering wheel will turn.
That's the way steering locks on that and previous generations of cars have worked.
The immobiliser does not stop the key or steering turning. It's pure electronics, so if you try and start the engine the starter motor won't get any power or the fuel injectors.
It is possible that the barrel or key has worn so the key won't turn, but as you are looking in the wrong direction when you consider this (or think about drilling it out!), I think the steering lock being triggered and wiggling the steering wheel while you turn the key much more likely.
I don't know why you are so keen to drill out the lock. If it is faulty, why can't it just be removed?
If it does need removing, and I think likely it won't, then have a look at the workshop manual, I'm sure it will tell you how to remove the lock...
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If you do change the barrel and get 1 from a breakers yard with its key, you will need the original key taped near the lock as the immobiliser chip is in it and the new key will have a different ID/code.