Steve, some of Ali's reply is correct some not quite so. Each pilot is trained and tested to fly the aircraft from their respective seat. An FO from the right Capt from the left. Training Capts are normally qualified to fly from both seats so they can train both Capt and FO's, and some (very few) airlines elect to train some line Capts in both seats although only to the minimum requirement (dealing with an engine failure on TO in the sim, single eng go around and landing) in order that they can operate in the right hand seat when crewing are short of FO's.
When it comes to steering on the ground the tillers are very much dependent on what the airline ordered from the manufacturer. Many airlines only have a tiller on the left and as such their SOP's mean all aircraft control on the ground prior to line up and post landing is done by the Capt. Other airlines specified a fit with a tiller on each side and as such their SOP's have a much more even balance of conrol. On the FO's sector they will taxi as well as fly. In this case taxiing clear of the runway would pose no problem unless as has been mentioned in this particular incident the Emergency services would prefer the room around the aircraft on the runway to manoevre.
Desmo - I understand and agree that each pilot no matter what their experience level should be able to operate single handedly and as such I'm sure most operators have some form of incapacitation training and would not allow line training to be considered complete without a level of proficiency being demonstrated. However good the training and simulation is, being in an actual emergency situation is quite different. As I'm sure your professional experience has made you aware.
Considering the uneventful outcome of the incident which originated this thread I think a degree of back slapping and praise for a job well done is well deserved. We are rarely called to put into practice all we train to do and most of us realise that no matter how experienced we are, being single pilot is not high on our wish list of daily occurances.
I'm sure that when you were a mere frozen ATPL holder you would have been utterly unfazed by the events this colleague of ours found himself in and would have considered it just another day at the office. For that I commend your superior abilities and calmness.
I would also recommend that you are aware that you may be putting yourself in an uncomfartable situation by travelling with any major airline in the UK, all that I know of use 200hr FO's, so in the event of an incapacitation, you may find yourself in the very situation described here. In that case I hope the training given to the crew matches that of our Ryanair colleague as do their abilities and, and another uneventful and unpraiseworthy (lack of) incident ensues.