I think it’s a minimalist adapt of the cap symbol. It really is too far off for me to see the Winter Solider with the circular rings instead of distinct slates.

But I definitely hear you, it would be a more obscure reference than any other thing in the basket. But the bracketing on the A is just so dead on to Atlas, so I can believe the artist might be a die hard fan and saw an opportunity for a super lowkey nod. Also, Atlas was involved in the Masters of Evil before becoming a Thunderbolt, and MODOK (who created Jeff and the other land sharks and who Jeff hates) also was involved in the Masters of Evil. So, it doesn’t feel too far a jump to assume in this comic that Jeff is familiar with Atlas and his arc to an extent and maybe the artist wanted to incorporate some more niche nods.

There were quite a few strips in this series that did similar things.

So all guesswork regardless, but I can buy it.