I think there is a Bug in t1??? For 2019.
There are 2 fields on status - 1. overall status - whether Resident / Non-resident; and 2. the other status is at a provincial level - what province did you live in - as of Dec.31, or the date you emigrated. So really three. I know. I am already confused too.
Those who left the country (from Ontario) and did not have significant residential ties with Canada put status as Non-resident, and the province from where the taxpayer emigrated as Ontario. With this -> TC does not calculate the ON Health premium - which is incorrect. See below CRA url.
https://www.canada.ca/en/revenue-agency/services/forms-publications/tax-packages-years/general-income-tax-benefit-package/ontario/5006-pc/information-residents-ontario.html#p7l81
Am I missing something or doing something wrong?
Yes. Here are the steps
Province of Residence is …
Residency Status is RESIDENT, not non-resident
Exit Date is the date of departure.
Residency Status of Non-Resident is for people who are non-resident the entire year.
@TimParris
I believe that the taxpayer may be a Schrödinger’s Emigrant … 
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“Those who left the country (from Ontario) and did not have significant residential ties with Canada put status as Non-resident, and the province from where the taxpayer emigrated as Ontario. With this -> TC does not calculate the ON Health premium - which is incorrect. See below CRA url.”
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"Line 81 – Ontario health premium
You have to pay the Ontario health premium if both of the following conditions apply:
You were a resident of Ontario at the end of the year
Your taxable income from line 26000 of your return is more than $20,000"
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The taxpayer was TAX-RESIDENT in the part of the tax year before he tax-emigrated, since otherwise it would have been impossible to tax-emigrate before the end of the year.
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