Quite so. The obvious thing to do is simply tell the solicitor that one has no 'up-to-date EICR' and then, as you say, "see what they say next".
If what they "said next" was to ask, or even attempt to 'demand', that the seller arranged (and paid for) an EICR (which I think would be very unlikely),
then, unless I were desperate to sell, I would get slightly 'confrontational', albeit pleasantly, in the sense of saying that if they wanted to commission and pay for an EICR, that would be fine by me, and I would make sure that their inspector had the necessary access.
Only if they responded to that by attempting to 'repeat their demand' would I tell them that it was up to them whether they wanted to pursue the purchase, but that there was no way that I was going to pay for an EICR, any more than I would pay for a structural survey, 'Searches' or anything else of that ilk
Kind Regards, John