The effort to disguise the Act’s true origins in Reconstruction bitterness
and racial hatred was overwhelmingly successful. The language of
misdirection grew over the years by frequent repetition that eventually
transformed a hate law into the respected shorthand for the general principle
that Americans do not want a military national police force.
Additionally, just about everyone examining the law focused on the false historical arguments instead of carefully analyzing the law’s actual text and historical
context.
Therefore, they missed, or ignored, the key fact that the original
Posse Comitatus Act was at least one-third pure fiscal law: Congress prohibited the expenditure of funds to use troops as “a posse comitatus or
otherwise to execute the laws.”14 This funding limit expired at the end of
the fiscal year along with a decisive, but temporary, exercise of congressional
power under the Constitution.15

Text from page 5 and 6.

After reading the argument(s) presented in this essay, it is easier to understand what the Posse Comitatus Act was meant for in the time it was used around the time of Reconstruction. The act was meant more for allowing racism to run rampant. Yes, the act in itself is/was a shield for racism in the Post-Civil War Southern States. It enabled the state and local governments to prevent blacks in general in the south from voting and having/using other rights.