Yes, but when it comes to suggestions about standard UI features, I’d be surprised if he disagreed. Apple sets a fairly clear precedent for how standard iOS UIs should work, and whether or not it’s in the Human Interface Guidelines, going against the standard Apple sets feels sloppy.
I would find it more likely that, even though (IIRC) the guy handling Instapaper’s support said he would pass it off to Marco, he simply didn’t see my suggestions or ever do anything with them.
I think you can maybe even make the argument that it doesn't matter if he agrees, if he's going against the HIG or even established standards then he's wrong about it.
This is definitely not true. Many of the best UI ideas coming out of iOS go against "established standards".
This is assuming the stuff is intentional, of course. If it's unintentional, it may simply be a low priority. Whether the UITableViewCell is de-selected during or after the animation is a pretty subtle and innocuous ui artifact that could nevertheless require deep changes under the hood to fix. If I was Marco, I'd weigh the impact of leaving it how it is, with the work required to change it, and probably end up leaving it until next time I reworked that area of my code. One man operations require tradeoffs pretty much all the time.
You can always use Pocket if you can't handle the occasional not-very rough edges this results in.