Stop being analitical!

[Emma May Smith]

Your claim that glyphs are chosen because of their shape requires more evidence than you offer. Much more evidence.

That k and t have different shapes is an observation. There is also no doubt that k and t are used differently. All I say is that it makes sense to write a smaller glyph if less space is available. 

In the same way it makes sense to emphasize the start of a new paragraph by using a gallow letter as the first glyph. Therefore it is an interesting fact that 93 % of the paragraphs start with a gallow glyph. Most times the paragraph initial word without the initial gallow can be found somewhere else in the text. See for instance word types like por, pchol, pchedy etc. Moreover p and f mostly occur on the first lines of paragraphs and many paragraph initial gallow glyphs are decorated with additional ornamentation.

Your observation is valid but your hypothesis isn't. The problem you face is that the word statistics for the line starts are often different from the main text (especially in Currier B). It's unsafe to use an observation for a single glyph when there many other differences. Any theory should attempt to account not only for the use of gallow glyphs in this position, but also d, y, s.