Martin didn't attend 2 of them. IMO it shows a lack of dedication to your full time job.
Martin didn't attend TWO DAYS, based on what is being reported. Missing two days is a big difference from missing two OTAs.
A lot of players in the NFL bypass voluntary work outs. Some guys go train elsewhere, some guys have personal reasons for missing OTAs. Some guys, like Randy Starks, completely don't go to any OTAs because they are unhappy with their contract situation.
It's not the end of the world.
All that was reported this offseason was that Martin worked very hard in improving his strength as that was identified as a weakness.