Looking at the G-hits, I would say this phrasing is exclusively used in the context of flexible working arrangements.

does not matter why
no hierarchy in reasons

Does it matter why a person requests flexible working?
Our research and pilot programme explored feelings around whether there was a ‘hierarchy of acceptable reasons for working flexibly’. Both managers and staff felt that:

It’s important to adopt a ‘reason-neutral’ approach to agreeing flexible working requests.
But it’s helpful to discuss the reason, in order to determine what type of flexibility will work best for that person/role.

"We should have a reason-neutral policy. Staff should only have to say why they need more flexibility so we can see what may work."

Line manager.

Same document:

You’re likely to see an uplift in candidates as a result; a study by Zurich found that job adverts which used gender neutral language and openly mentioned flexibility attracted 20% more women (as well as more men).

https://timewise.co.uk/articletopic/diversity-inclusion/

It is therefore the intention of Red Dragon Manufacturing Ltd to be flexible on working patterns for all employees regardless of personal circumstance and we operate a reason neutral.

https://www.reddragonflagmakers.co.uk/pages/flexible-working...

reason is immaterial

Flexible working should be ‘reason-neutral’

For employers, implementation can prove daunting as it can be hard to know where to start, particularly if they’ve not formalised these types of policies previously. At our roundtable, all attendees agreed that flexible working should be reason-neutral, meaning that an employee shouldn’t need to give a reason to want to work flexibly.

https://tiger-recruitment.com/workplace-insights/looking-imp...

employees are perfectly allowed to have their own reasons

Flexible working
We support and encourage flexible working so work can fit around your lifestyle or demands whether that be as a parent, carer or simply want to explore opportunities to enhance your wellbeing and create a better work-life balance. Our mantra for flexible working is ‘reason neutral’. What’s important to you, is important to us.

https://www.wessexwater.co.uk/careers/inclusion-and-diversit...