Adam and his boss, Oscar, can't talk face-to-face right now, they are at different locations and will stay like this for some time. Oscar is quite conflict-avoidant, more of a talker than a doer.
Adam is new in the company and currently working on an important project with multiple issues, which nobody managed to solve for many months before he even started at the company. The main stakeholder and roadblocker is Tom. Tom is an ego-driven extremely ambitious person. His seniority is the same as Oscar's. Both have had some problems with each other in the past, but aren't enemies.
Tom finds Adam ok, their relationship is normal.
Tom talks to Adam (verbally) at length about a major issue. Tom tells Adam among others that he won't move a finger to correct the issue. Adam then writes his boss, Oscar, a short, very factual summary of the conversation ("Tom said he didn't see The Very Important Issue as a priority and stated he wouldn't help").
Oscar forwards the email to Tom asking him whether he really meant that.
Hell breaks loose.
Tom calls Oscar telling him that Adam is stupid and unfriendly and ugly (yes, I'm being slightly sarcastic here) and he doesn't want to work with him again.
Oscar blames Adam's lack of communication skills and gives him a long lecture about people's skills and how important it is to talk to people and to be friendly and similar.
Adam feels the only stupid thing he did was writing an email instead of calling (although he could have been quoted by Oscar even if he had indeed called). He feels scapegoated. Still, he wants to solve the situation. What is the best way to solve that? Should Adam bring up with his boss why the problem appeared in the first place?
P.S. As you can imagine it's not a theoretical situation. I'm Adam.