If Trump refuses to hold press conferences (as Hillary did not hold a press conference in 2016-according to the Washington Post, who actually tracked that information) is the media then relevant as a source of information about him?

Presidential press conferences peaked under George W.  at 210 and have gone down in frequency since. Obama is at 162.  Reagan only had 46 and Jimmy Carter 59.

If Trump can get his 'message' out through Tweets or surrogates or even in  puff pieces like the one I stumbled across last night on (gasp!) Fox or in 60 Minutes one-on-one interviews, what relevance media he does not select?

The media doesn't relish a 'traditional role as outsiders', it relishes getting information published that is 'exclusive' or sells to the benefit of  their advertisers.