So he's been grounded pending the crash investigation - this is standard procedure for many airlines
So he's lost his flying pay while he's not flying - this is standard for any pilot (and many instructors)
His desire to leave BA may be BS. But it sounds he is not being defended by the airline, and that he feels he should not be on lower pay while grounded.
My sypathies go out to the crew who are stuck in a world where the lawyers are keeping them (and BA) gagged pending the end of the investigation/legal debates, meanwhile the press have freedom to speculate (in some cases totally recklessly). Your turn will come later boys - if BA doesnt want to spend money keeping its pilots' reputation brightly polished, then lets hope BALPA can. Otherwise, the pilots should keep a record of every piece of BS that makes the press and get some damn good lawyers once this is finished.
Glad to hear that the crew appear to be getting more than their basic "on ground" pay.