Mt Kenya is a sensational place, either for trekking or for technical climbing. As you already seem to know, 5 days isn't really sufficent to get the best out of it. However Pt John has great rock-climbing without the same level of commitment as the main summits (unless you take on the multi-day aid routes on its steepest side.). From memory the route I did on PT John had a very short crux section of around Gr 17 (in an awesome location).
I wouldn't sweat too much about taking ice gear, I've climbed both Neilon and Batian without carrying crampons or ice axes. The bivvy hut near the summit is an amazing place to camp, one of the best sunrises ever, the rap descent on the Normal route is all bolted and the rock on the well-travelled routes tends to be pretty solid. Otherwise there is plenty of other great climbing in Kenya if you just wanted to do some cragging.
Dave