...or an unintuitive interface leading to an incorrect expectation.
Just because something doesn't work as you might expect it to (without reading the manual) doesn't make it a bug. It could be considered poor design, but not a bug.
The fact is: there are similar annoyances with HDR-FOX (but not identical ones). On that, if you decide to instant-record a programme you are watching, the recording starts at the current time. Should you want to record the whole programme from the start, you have to wind back through the TSR to the point you want to start and then press record (assuming you have been on that channel from the start). I would argue that is intuitive.
What is less intuitive is that having pressed record, the damn thing skips to the live broadcast point - which you wouldn't have wanted if you were already watching timeshifted and decided to record the end of the programme for later. Yes, this may well be necessary due to the design of the TSR etc, but is nonetheless not ideal.
Similarly, if you are watching a channel timeshifted, and then (live) a scheduled recording on the same channel starts, play resumes live and there's no way back to the timeshifted stuff so you miss the end of the programme you were watching. Again, probably an unavoidable consequence of the way things are implemented, but if the unit had been deliberately designed to be absolutely intuitive this would have been considered a defect (but the HDR-FOX would have ended up priced out of the market, and late to market by missing DSO).
In the case of the 5000T, they seem to have addressed one problem and introduced another as a byproduct (and by consequence of the limitations). I suggest the result is less intuitive rather than more.
So there you go. The point is to work out what the compromises are, and learn ways to avoid them or live with them... and each product requires a new learning cycle which is why we like to stick to what we've got. Few products are perfect, any that are perfect are usually very expensive, and the only way to find the perfect product is to buy them all or rely on reviews and hope the reviewer isn't biased and is as picky as you (and has spent long enough looking for faults - which makes the review untopical).