Rescue Rabbit Rulling

Hello,

My opponents controls a Rescue Rabbit and three others monsters (so four monsters in total).

Can he try to banish his rescue rabbit to summon 2 monsters ? I don't think so since when he activates the effect of rescue rabbit first, he doesn't have enough place to summon two more monsters on field.

Am I wright ?

Thanks.

His own banish is a cost so he is never on the field with the summoned monsters. Since you can always pay the cost of a cards, it can activate and since the space is there upon resolve the 2 monsters get summoned.

You can even perform Synchro Summon, Fusion Summon, Ritual Summon and Tribute Summon when full field, so why can't Rabbit use its eff to summon 2 monsters?

Yes, because Rabbit will be off the field (so two slots will be open in the Monster Zone) when your opponent Special Summons the two Normal Monsters.

They can activate Rabbit eff.