Unicode: half-റ്റ: to encode or not

There are my reservations on introducing half-റ്റ:

1. It can violate Uniqueness Rule because half-റ്റ and റ will have same rendering.
2. We are standardizing graphemes (ലിപി) in Unicode; not phonemes (വർണ്ണം). Please refer this article to understand clear distinction between the two in the context of Malayalam.
3. Is this a better solution to any existing issues?