As I posted elsewhere, the base dimensions, when folded, are probably 18 X 16, as is in the rules. However...
The chair back really angles outward, which takes it probably a good 4 inches past that 16 total allowed. So, from that regard, no, the chair isn't fine.
Add to that, the chair also does not come with the ability to latch onto the front of the bench. Most "good" chairs have that little clip thing that does this. Since these don't clip on, you can't help but slide back. So, again, no, the chair is not fine. Even if they rigged up a way to clip the chair on, that back lean is still a problem.