That’s your subjective opinion. And as you say elsewhere: “That’s not how science works. Conclusions are not based on subjective opinions.”
How does the ateleological perspective predict this? Would the perspective have been in trouble if different glutamate-gated ion channels had evolved de novo for different functions?
I do understand that. I could also have written “The common ancestor of plants and animals is not believed to have employed nervous system-like signalling …”, which would have been a wordier way of making the exact same point.
“Exaption” is just a label attached to a phenomenon, it’s not by itself an explanation for that phenomenon. The ateleoligic explanation is that a structure that was selected to function in one organismal context just happened to also work well in a different organismal context.
And that explanation may also be correct in many cases, especially those with a low degree of specificity - like the evolution of the mammalian middle ear from reptilian jaw bones, where ears can be constructed from different bones.
But when it comes to cases with a high degree of specificity - like multicellularity evolving mulitple times independently, each time using the same ancient molecular machinery, which is non-essential in unicellular organisms - that arouses my suspicion of design.