While it'd be nice for bitcoin "companies" (companies profiting from Bitcoin transactions) to contribute to core testing, it seems like they may only do so if they have to. Maybe now they will consider it? But in my opinion it'd be more likely they would want to throw money at the problem, rather than get their hands dirty.
It's utterly disgusting how greedy some of the leading companies in this space are, and just how fraudulently their leaders tend to represent themselves with statements of support/belief in Bitcoin or similar. AFAIK, blockchain.info has hired 1 employee (although I can't recall which whop) and there was a Xapo listing for a Bitcoin Core developer some time ago (I'm not sure what happened with that). Other than those two, I haven't seen other examples of companies doing this.