Style vs. Date Of Creation

Methods of 21st century organ building are exploring the boundaries of the art these days in many diverse ways (photo).
The same can be said of organ composition.
"Post-modern" composers are continually making contributions to 21st century organ repertoire [See blog, Themes].
With so much new music being written by so many new composers the question arises as to how we should perform this repertoire, especially a modern fugue where it's written pretty much in 18th century common practice style.
The general thinking or "rule" prevalent in music schools dictates that any organ music composed during or after the 19th century (post-1800) be performed legato as a starting place for the touch and to employ all of its associated techniques (substitution, thumb glissando, liberal use of the heels in pedalling) unless otherwise specified by the composer [See blog, Touch, Parts I-V].
We also know that no rule with organ playing is ever "absolute" -- there is no such word in the glossary of organ playing.
When we encounter the Bach fugue (or any fugue from any century written in a very busy contrapuntal style with independent moving parts proceeding at a brisk tempo), knowing that the entire effect of a polyphonic piece like this stands or falls on the clarity of its moving lines, the style of the piece necessarily takes precedence over its date of creation when it comes to selecting a touch that best brings out all that this music has to offer.
In this situation the style of the music dictates that the moving notes be performed with a clean legato (imperceiveably broken) or a broken non-legato mixed with ALL other types of touch depending upon note durations, their rhythmic patterns, whether a note repeats, the way the instrument breathes in its own acoustical environment, and the tempo [See blog, Touch, Parts I, II, Rope Pull].