Unlike the example in the link you give, η isn't a generic random name like a,x that can mean anything. If you ever read a paper on stochastic gradient optimization, you'd know that η means learning rate in the context.
It is bikeshedding because it is analogous to insisting that using "angle" instead of "θ", or "radius" instead of "r" in a 2D geometry library is superior and takes your code from being a lackluster to something that shines (in the words of the original author), while not having anything useful to say anything about the mathematical/technical aspects of the code itself.
Here is the definition of bikeshedding:
> The term was coined as a metaphor to illuminate Parkinson’s Law of Triviality. Parkinson observed that a committee whose job is to approve plans for a nuclear power plant may spend the majority of its time on relatively unimportant but easy-to-grasp issues, such as what materials to use for the staff bikeshed, while neglecting the design of the power plant itself, which is far more important but also far more difficult to criticize constructively. It was popularized in the Berkeley Software Distribution community by Poul-Henning Kamp[1] and has spread from there to the software industry at large.
from https://en.wiktionary.org/wiki/bikeshedding