No. No touching, please- especially not the unexpected or sudden type. John won't say anything about it, but getting in his personal space will make him incredibly tense and awkward.

The exception to this rule, of course, is Sherlock
j/k!!

No. The no touching thing applies to everybody. His sister included. Getting past his block in this regard is always going to be a major hurdle in any future relationship, which may be one of the reasons he works with Sherlock so well. Theirs is a kind of intimacy without any form of threat (of making a fool of himself if and when things get physical) carried with it.