If the problem is that this guy is forcing you into position using his strength, then the solution is to not resist him in any way
At first this is counter-intuitive, as you feel threatened so you tense up and try not to move, but this will only make the situation worse.
If his aikido is any good he'll still be able to apply technique. If it isn't (as you suspect) then he'll end up rotating your arm like a propeller without taking your balance, and will not be able to apply technique
Attack him slowly and let your arms and body relax so there is no force going into / towards him, and see how he deals with it
If he asks you for more resistance, just say that you aren't confident in your ukemi yet so you'd rather work at a careful pace.
Hope that helps,