"I believe it is a man thing" is not a good response.
Condescending, dismissive, etc. We have words for it.
We have the word late and the word tardy, so why do we have black people time?
These terms do something completely needless for bad reasons.
I mean...it is a man thing. The same way white people have a certain level of racial animus, men have a certain level of sexism. That's what happens when you live in a society built specifically for you.
The concept of "black people time" exists specifically because of white people stereotyping black people.
dude
You need to reexamine your assumptions.
There is a case for "it is a man" thing, but not in the way you're seeing it. Men are more likely to challenge authority, but that doesn't actually fall in line with the idea behind mansplaining. They are more risk taking, which may lead to them challenges others who society recognizes as experts. However, neither of those things fall in line with assumed authority, condescension and dismissive attitudes. A women with risk taking and disagreeableness would exhibit the same behavior. There certainly can be a legit "mansplaining", but its rare enough not to require the sexist phrasing and certainly not common enough to justify its frequency of use.
Also, society is not specifically built for any single person. I kind of need to know where you went wrong in order to address you on this any further. Perhaps I should ask why black time is stereotyping but mansplaining is not?