Hi T-con,
As per my understanding from your description and screenshot, would you like to hide specific fields based on Status reason on the quick create form?
It seems that you could customize quick create form of opportunity close, so I assume that you had been working in online environment with wave 2 release.
If you would like to work with javascript, then create a timer to get field value and insert the web resource to Opportunity Close form under Opportunity Close entity.
function test() {
setTimeout(() => {
alert(Xrm.Page.getAttribute("opportunitystatuscode").getSelectedOption().text);
}, 2000);
}
I could get value both for Close as Won and Close an Lost from my test.

In business rule style, I created a rule for Opportunity Close samely.
(Scope: All Forms)

In Close as Lost test,
By default the Status reason equals Canceled, after I switched it to Out-Sold and set it to Canceled again,
then Description field would be hidden.

It seems that business rule wouldn't take effect for default value,
In conclusion:
always hide field -> javascript on form onload(timeout)
hide field on condition -> business rule or javascript on field onchange
Regards,
Clofly