No, it does not conform. As I wrote earlier, I have not seen that usage for less than 100%. So 600% conforms; 50% does not.
That is, expressions like "twice as slow/thin/short/..." or "2x as slow/thin/short/..." or "200% as slow/thin/short/..." have a well-established usage that is understood to mean "half as fast/thick/tall/..."
But "50% as slow/thin/short/..." or "half as slow/thin/short/..." have no such established usage.
For some evidence to support my claim, please see this 2008 discussion on Language Log:
https://languagelog.ldc.upenn.edu/nll/?p=463#:~:text=A%20fur...
Since HN has a tendency to trim URLs and might prevent this link from taking you to the relevant portion of a rather lengthy article, I'll quote the salent bits:
"A further complexity: in addition to the N times more/larger than usage, there is also a N times less/lower than [to mean] '1/Nth as much as' usage"
"[About this usage, the Merriam-Webster Dictionary of English Usage reports that] times has now been used in such constructions for about 300 years, and there is no evidence to suggest that it has ever been misunderstood."
> I have not seen that usage for less than 100%. So 600% conforms; 50% does not.
> For some evidence to support my claim
Please note that the 2008 discussion you linked does not support your claim in any way, so 50% does conform.
I guess we will have to agree to disagree.
I believe that the history of English language usage is replete with examples such as "X times less than" when X > 1, but similar constructions for X <= 1 do not appear with appreciable frequency.
In any case, I think that continuing our conversation is unlikely to be productive, so this will be my last reply.
I will just say in closing that our conversation is a good example of why the MAGA folks have probably chosen phrasing such as this.
To be fair our conversation can be summarized as:
> only pedants misunderstand this, here's a 2 decade old source that doesn't support my claim, I rather not continue the conversation
so it was never meant to be productive