The IRA want rid of Jimmy for doing things they do not like, but they do not want to get rid of him themselves as it would cause internal conflict/make them seem like they have internal conflict to their rivals.
Jax's baby being stolen was a stroke of good luck for the IRA as it means they could blame Jimmy for this. Jax, however, has now found out Jimmy does not have his baby and that the IRA have him. The IRA will only hand over the baby if Jax et al kill Jimmy. The Sons of Anarchy America will therefore kill Jimmy, thus solving the IRA's problem. The only problem is, however, that the Sons of Anarchy Ireland have been working for Jimmy for a while now and some are loyal to him (the sideburn chap) whereas others are unsure (the older grey haired tall chap).