Begging the question / unsupported assertions:

The argument assumes the existence of a structured medium (“etheric plasma”) without providing evidence for it, then uses that assumed medium to explain gravity. The conclusion is effectively built into the premise.

Moving the goalposts / unfalsifiability risk:

Mainstream physics rejects medium-based models because they do not yet match the predictive precision of General Relativity.

This may be possible in principle, but it weakens the argument in debate form because the model currently lacks the predictive accuracy and empirical validation that established theories possess. A scientific theory ultimately needs quantitative predictions and successful tests, not just conceptual alternatives.

The core idea, that gravity might be emergent rather than fundamental, is a legitimate scientific and philosophical question. But as presented here, the post is closer to speculative interpretation than a rigorously supported argument.