I don't necessarily think he hadn't already learned, or at least begun training for, rokushiki before the skip. I just chalk up his not using them to not having mastered them to a degree useful in battle possibly combined with some personal preference. Personally I wouldn't really like shigan, because I'd rather punch someone than stick my fingers inside them.
Well he only used soru before he got wtfpwned by luffy so its possible he didnt have time to use the other techniques