I disagree with Lewis' stance on this in general, that it's too divisive
Being "too divisive" is like being "too pregnant."
Anyway, there are lots of people who won't be attending or watching the inauguration. Lewis just gave his reasons for not going. Let's leave out the issue of whether disrespecting the president by questioning his legitimacy is divisive. If it is, it's certainly not Lewis who started it; and, I won't hold him to a higher standard than any other politician. So, if Lewis and others stand and call Trump a liar on the floor of Congress during his State of the Union address, people will say that it's disrespectful. Would it be divisive? I guess it depends on how one took it.
Anyway, the issue of Trump's legitimacy is really separate from any demonstration about it. I.e., just because Lewis says that Trump is illegitimate, that doesn't make it so. Remember. Anyone can claim anything about anyone, and anyone can believe it if he chooses to. Those are the new post-truth rules, no? I could post links to plenty of bloggers who make claims about Trump and friends. Are they true? Dunno. Are they automatically false? Dunno that either.
Anyway, if Lewis kissed Trump's feet on inauguration day, there would be no less division. The only way to not be divisive is to be cooperative and help each other. "Love thy neighbor," "do unto others," etc. Yes, that is precisely the approach Lewis and others used in the 60s to fight segregation. Yes, if Lewis took the same path today, it wouldn't be divisive. It might be better; but, otoh, from his pov, it'd be going back 50 years. So, I think there's more than Russia involved in Lewis's protest.
50 years ago, though, I was also against "protests" and "demonstrations" because they just waste energy. That includes getting upset about other peoples' protests. Arguing about whether Lewis or Trump is divisive is divisive. I am not going to act any differently toward anyone or group because Lewis doesn't attend, no matter what his reason was. I think there are people who'll say "See, see" and use it to confirm their opinions, beliefs, prejudices and to justify their actions.
"A man is rich when he has time and freewill. How he chooses to invest both will determine the return on his investment."