The Kenyan duo had travelled to Cyprus in early January to join Division One club Lakatamia FC.
Ayimba and Rombo managed the Kenya Sevens teams in the rugby union version of the game.
It has been 82 days since the Spanish top-flight suspended fixtures.
Ighalo could prove an important addition to Ole Gunnar Solskjaer's squad.
He said he wanted to make it clear that his actions against the man, who is white, were not racially motivated.