This is just plain wrong. There are many ways to handle such a situation. One would be "visstidsanställning" which is employment for a pre-determined period.
Sure, you can work around the labour laws in many ways, but he is likely referring to a normal full time employment contract as most people do when they talk about employment.
And he's not wrong in the figurative way, the labour laws are quite strict and the unions are in an impossibly strong standing in Sweden.
You can fire people if you don't need them (don't have enough work for them), that's called arbetsbrist and is the most common reason for firing people in sweden. You just can't turn around and hire other people for the same job right after.