It seems to me that Starmer’ 10 pledges are a decent basis on which to challenge the government right now when the government policy is in question and the media are getting critical. If Starmer is shy about highlighting his pledges now, when will he?
The Labour brand is soiled which means Starmer is on the metaphorical back foot. He needs to tread carefully and deliberately at the moment. There's enough material being generated by the government's response to the virus to keep him busy challenging the government for a while yet, and Brexit is coming. I suspect/hope he working on what he wants Labour to stand for under his watch in the background. The media may feel uncomfortable because he's a little boring and doesn't generate drama, something I personally welcome.