It is important also to understand that venus / ketu have opposite gunas; and on physical level, ketu does hammer (curtail) venus's natural significations.
Important thing - In interpreting ketu :
a. we must always look at its sign dispositor (as that ruling planet becomes karmic controlling planet) and ketu become its karmic agent. In the example quoted - guru is KCP and ketu becomes the agent of guru
b. If rahu / ketu are associated with yoga graha of the lagna and placed in kendra / trikona - then only they become shubha; else they are considered ashubha for the lagna in question.
c. rahu / ketu, if associated with maraka planet - will be troublesome during applicable dasha bhukti and their respective transit in 1/ 7 from such placements. This becomes all the more critical, if maraka planet is its sign dispositor (which is not there in the chart quoted). and if planets engaged are "krur" and such association is in maraka sthana (or dusthana) - then one must be careful from fatal incidents. I repeat again - such an association will result in bad events only during applicable dasha / transit.
venus is the purest of the planet (without pure sukra in chart - spiritual achievements can not surface (though spiritual /religious knowledge may be abundant), and its affliction must be seen by the gunas of afflicting planet. Perhaps, ketu being spiritual planet (with KCP being guru) - does not damage the moral (for any sort of sansarik bhogas) and; this might enhance the philosophical / religious rituals related inclinements as well.
Neither naked asceticism, matted hair, dirt, fasting, sleeping on the ground, dust & mud, nor prolonged sitting on one's heels can purify a man who is not free of doubts.
SURRENDER JOYFULLY TO THE WILL OF THE ULTIMATE DIVINITY AND RELISH THE TASTE OF ABSOLUTE BLISS.