Should a party of two (2) be seated at a table or booth that can seat four? It is hard to believe how this has become a standard for many restaurants that they will not seat a 2 at a four for fear of losing the potential of a 4.
If I have a party of 2 in hand and the table of 4 is vacant you're damned right I would seat them But if I know that if 2 seats will be coming up I would ask them if they would wait a few minutes. But I would not be discourteous in making them wait too long.
Two friends of mine went to a frequently used restaurant at 3 pm and seated themselves at a booth for 4; the host and then the Manager asked them to move because it was their policy was not to seat a 2 a booth for 4. Needless to say the regular customer was upset at being asked to move at an obviously quiet time with the 4 not being need.
He wrote the Manager Owner and received a long rant that they could not make exceptions to policy otherwise other customer would take the same privilege.
This is a neighbourhood restaurant that has now lost to neighbourhood customers.
Continue with your policy and you will have more than enough empty tables of 4 to seat many 2s.