Actually, I do entertain the possibility of bacterial activity on Mars.

But I believe you may be letting your logic lead you too far. There are others here far more adept at applying logic than I am, but I like to think that I engage appropriate geo-logic. It's actually a bit different from standard logic. I highly recommend a book by Robert Frodeman called "Geo-Logic". It's quite indepth, and an excellent insight into the study and practice of geology. I don't have the time to give it the review here that it deserves.

Which is more logical an assumption?

OB's: Wishstone has a poly-crystalline texture with some well-formed crystal shapes of various sizes and rounding, and a fine grained matrix. Differences in weathering of crystal forms and possible psuedomorphic replacement noted. There is a white, botryoidal crust developed on the surface. Fresh rock returns higher than average values of Titanium, Phosphorus, Calcium, Sodium, and Potassium. Magnesium, Chromium, Sulfur, Nickel and Bromine are relatively depleted.

Context of observations: specimen is from an area completely dominated by mafic igneous rocks.

Working Model:
Specimen is a mafic igneous rock of unique composition (mafic igneous systems have a wide range of possible chemistry), that may or may not be related to the underlying bedrock. If it is related, there may be other specimens up hill, or it may be a small, localized intrusion: a sill, a dike, a pipe. It may have been transported here as ejecta of igneous or meteroric origin. Crust is derived by the selective weathering of suseptable mineral phases deposited as caliche.

Recomendations:
Elemental testing of crust.
Testing of at least one other specimen.
Check for a train of float of similar rocks as traverse progresses.
Further study of data as it becomes available.
Review phospate and titanium mineralogy and associations in igneous rocks. Secondary review of sedimentary rocks.

Or this?

Observations: "there is a great deal of three dimensionality"..."everything is crumbly, there appears to be many embedded rounded pebbles, the matrix appears to include hardened clay".

Context of Observations: "Earth, water, panspermia, billions of years ..." ie: There just has to life on mars.

Working Model: "it was impacted shocked, fractured and melted and then frozen and remelted in a water rich environment, I believe these are shocked fossil conglomerates derived from a water and biology rich environment over a basaltic foundation."

Recomendation: "They need to quit enforcing this 90 day spectroscopy embargo!"

It's your model, have fun with it.
jms