I'm not convinced the arbitrage trade is really what's going on here.
SCTY is ahead of where the merger ratio says it should be relative to TSLA by about $0.12 per share, based on TSLAs drop. ($2.79 * 0.11 = $0.31, vs the $0.18 or so SCTY is down). That certainly suggests some strength in SCTY due to a closing arbitrage gap, but both shares being red doesn't make sense.
SCTY is the one that is being manipulated here (it can be done with much smaller number of shares). If you control price of SCTY you have risk free way to control price of TSLA. It's already going on since August.