I see a large number of negative replies to that tweet.

So, now that some time has gone by and the dust has settled, I wonder: was the 100k marketing gag worth it? I do not think it was.
It does not seem like it was a well-thought-out PR stunt because there appears to be minimal traction. It did not gather as much attention as they hoped it would. If anything, a lot of people are viewing it negatively.
I am sure 100k is nothing to Gemini anyway.

You have a point, but I think the major reason behind the collaboration between the Mara and the Gemini exchange is not about gaining traction, because it is something they easily achieved by paying bloggers, crypto news platforms, and other influencers to do the assignment, once the major forces in this space announcement the transaction other influencers will do the same.
How do you think some shitcoins get huge traction?
According to the link provided by ABCbits, the major concept is to honor Bitcoin Pizza Day which other crypto related platform does the same thing but in different ways.