In the real world, what's going to make Python less accessible to PoC new to programming(and new programmers generally) is the arbitrary change in well-defined industry-wide terminology. Working from documentation and learning resources that employ master/slave when those terms have been memory-holed in the newest versions of the language is the sort of seemingly minor change that trips up neophytes.
I'm not totally opposed to changing master/slave. But in light of the real cost of this sort of breaking change I'd want to see some evidence of actual harm, rather than some guy(who, I feel compelled to point out, is a white man) insisting that we change it for what are, at best, totally theoretical and speculative harms.