You're right. I'd rather have Ryan Goins, Gift Ngoepe, Yangervis Solarte, Darwin Barney, Chris Coghlan, Rob Refsnyder, Cliff Pennington, and Munenori Kawasaki waiting for the inevitable injury to happen instead of a capable MLB player who can also cover the backup catching role. f***. 4,000 plate appearances given away to replacement level ball players at 2B/SS/3B since the day Goins made his debut and the instant it starts to look like the team has some solid depth on the infield, people want to trade it away.
Martin is not going to take away any playing time of note from the young guys, unless the team hires Cito Gaston to manage again. He's not even going to take up a roster spot over anyone other than Reese McGuire because you need the second catcher anyways.