It's not an assumption, the commenter also clearly stated, "I hope that's constructive". To some of us, it sounds belittling and dismissive, regardless of how well he knows his company better than us.

There is a big difference between "I don't believe you were trying to be constructive", (which make assumptions about intent) and "I found your critique to be un-constructive, here's why:"

The former adds nothing to the conversation and is pretty close to being a personal attack, the latter provides feedback and (may) prompt constructive debate about how to provide critique.

Sure, here's why it's not constructive: not once in the parent comment is an alternative suggested or a question raised.

Just a list of things that are "wrong," according to the poster.

It's a resume piece and the parent works for a design company. He's not looking to start a discussion on the merits of the design and how to improve it, only his problems with it from a hiring perspective (polish, consistency, lack of research). It feels very constructive to me.

Then what separates constructive criticism from just criticism?

Parent comment supplied criticism – I'm not arguing that. But s/he did not at all help to reveal a path towards a better outcome. That's what would make it constructive.

Judgements on motive, while critical for investigations and character analysis, are obviously irrelevant to online tech discussions, famously impervious to baggage, ideology, and petty warble.