Yes, I believe it was more from apologetics. I don’t have so much contact with OT studies.
(i) I suggested it because chronologically the Roman period overlapped with the period of applicability of OT law (which would presumably have extended until the dissolution of the Jewish state as a separate, if subordinate, polity after the First Jewish-Roman War – though I think I read somewhere that the OT practice of slavery for Israelites ended with the the destruction of the First Temple), (ii) Rome was the largest polity of this (later) period, & (iii) Roman practices are well documented.
I think, in context, the issue is more what Biblical precedent can be found for and against the practice of chattel slavery (particularly for out-groups – non-Israelites then, non-Europeans in more modern times), than what the varied practice was over the centuries of the existence of an ancient Jewish state (which may have been highly influenced by the relative strength of that state comparative to its neighbors at various times) might have been.
Yes, I not-uncommonly find myself spending more time fact-checking apologetics than actually reading it. I suspect to an extent I’ve come to subconsciously regard it as a performative art (similar to watching a stage illusionist’s show) than an informative art. 
But I’m just watching from the ‘peanut gallery’, and do not see myself in some way responsible for cleaning up their messes after them, as Biblical scholars and scientists at Christian institutions (e.g. @stlyankeefan’s comment here) may.
Addendum: oddball question, how is Apologetics regarded in terms of serious scholarship by the wider Christian academic community? I know that many (most?) atheists regard it as simply a form of propaganda, but I know that some Christian institutions of higher learning have whole departments dedicated to the field.