Not that I would be in need of this feature right now, but I thought it would be better to say something now - rather than to complain later when I’m in dire need and/or angry:

As someone who doesn’t own a mobile phone of any kind, being able to use two factor auth via email would be the only way for me to use that feature.

That being said, I’m being told that a self-made Captcha (which you would have full control over) could be written in less than an afternoon. There are so many talented programmers on this site - you could hold a small competition and pick the best one. ;)