That was REALLY weird to read. In reader mode the comparator in the first conditional was >=. But without reader mode it was just >.
Though a gap in their process is that, as you mentioned, various reading modes also remove styles and likewise might see it. Though a reader should filter out opacity:0 content.
Not just an "AI solver", a Python interpreter will also do it "wrong". The idea is that it's so simple that anyone qualified should be able to do it in their head, so they get the answer without the equals sign (but IMO a qualified applicant might also know it takes 5 seconds to run it in the repl and it'd be better to be correct than to use the fewest tools, or might be using a screen reader).
But then the question is, how do you reach people who filter out the job ads?
It also excludes users of Lynx, cURL, possibly people using accessibility tools, those with custom/overriding style sheets.
Thus, if you get the wrong answer, you "cheated" (or used reader mode)