Because Wilder has started to see nightmares of his fights against Nichols and Sconiers. At those nights Wilder was badly beat up by them. Wilder also got heavily rocked and almost stopped by 48 year old bloodpressure patient, who grew up watching Ali-Foreman 74' live on neighbours tv. Without referees help Wilder would have most likely lost those fights. And if Joshua-Wilder happens in the UK, Wilder won't get any personal help from the referee.