It is a difficult issue. I do a mathematics and computer science degree hence there's obviously no real lack of mental arithmetic maths skills for this degree (well, at least the basics are consistent across the maths students).

Anywhoo, this is - IMO - something that the author's college should look at collectively. If there are some students and professors with massively different ideas of the required level of mental maths skills, perhaps the college should look at introducing a mandatory first year 'mental maths' crash course/module?

This would help to make things a little more consistent. If there's genuine confusion/disagreement between the students and Professors, this should - IMO - be addresses by a course-wide decision being made.

Regarding programmable calculators - they can be reset in about 2 seconds total (it's usually Menu -> Settings -> Memory -> Reset All).

In our University, the exam invigilators ensure that all programmable calculators are reset (with them watching them being reset, of course) before the start of the exam.

So I'm not sure why this (to me) fairly obvious idea seems to be overlooked in the article? As I say, it takes 2 seconds total.

An interesting article though; even though I think the author/prof is approaching things in a slightly muddled (for want of a better - non insulting- term!) way. The college should (IMO) decide on how they want to approach things, and then be consistent across all modules and all Professors.