I think that it is not too subjective, at least not compared to other questions. Seeing that the question already has useful answers it is possible to answer. Any question where it is hard to tell what would be most useful for the OP is subjective in a sense, but if this seen as a reason for closing questions *lots* of questions will have to be closed.

Also, questions based on actual problems are encouraged. This question is based on an actual practical problem, namely that when a user suddenly only can use one hand, then Ubuntu (as most other systems) is less efficient and more straining to interact with.

Finally, it might be argued that the question is too general and therefore subjective. I think not. It makes sense to pose the problem generally because using Ubuntu with one hand, rather than two, is a general problem. It is a problem that some users are likely to face (of course, this does not mean that particular questions on using certain programs with one hand lose force). Some solutions to using a particular program with one hand are applicable to any program because they rely on something external to that program, e.g. some system feature. Such solutions are fitting answers to a question on using Ubuntu with one hand.