You are arguing the wrong point. In the current purchase tiers, there is no "$10 version," right? There is a $20 tier that you can buy for $10 on sale. You can download the latest version immediately upon release. I bought it about 9 hours ago and had no issue downloading 0.15a. There is a $2 tier that you can buy for $1 on sale, and it will be one version behind the latest release.
Now, I don't know if there was only a $10 tier and no $20 tier before. If there was only a $10 tier and no $20 tier, and folks bought the $10 tier (whether it was on sale should be irrelevant to the purchase tiers) thinking they were buying into the top tier but actually buying into a hidden second tier with delayed access to the latest version, then I think you have a legitimate complaint.
In FEYADA's post, it only said that "If you spent [emphasis mine] $5 - you will receive a new version in 1-2 weeks after release." This statement should be construed only as a promise that if you bought into the hidden $10 tier on sale for $5, you will receive the new version 1-2 weeks after release. If you buy into this tier after FEYADA explained it and do not get 0.15a in 2 weeks time, then you have another legitimate complaint.
I was tempted to spent $5 (sale price) under the current tiers just to see if I get 0.15a in 2 weeks. Because of what I saw of the free 0.8 version and certain posts I saw by FEYADA in the comments, I opted to just give a bit more support and not deal with the hidden tier with delayed access, which is really more suitable for Patreon than Itch.