Mr. Biden’s hesitancy to engage with top-of-mind issues reflected the risk-averse approach he has taken to several facets of his campaign, including limited interactions with voters who might challenge him and relatively few exchanges with reporters during a period of restricted travel and press availability because of the coronavirus.

And it underscores the gamble Mr. Biden’s campaign has made for months: that American voters will reward his sober, measured approach to politics that stands in sharp contrast to Mr. Trump’s.

But presidential nominees typically are not so circumspect about issues that energize their parties’ bases — especially, in Mr. Biden’s case, younger voters and progressives, many of whom did not initially support his candidacy in the primaries.

Told in the session with reporters that protests were expected on Wednesday night in response to the grand jury’s decision on Ms. Taylor’s death, Mr. Biden said that “they should be peaceful.”