I don't think it's been all that sudden, to me it's been building up for a while.
I didn't like him during the Mad Sally debacle, but especially during the Laurel/Marlon story he was being very passive aggressive and a bloody sap. I wanted to give him a good punch in the gob then.
I agree it's going to be an elder abuse storyline and it's already rather disturbing and horrid. Poor Sandy can be a pain in the arse, but this is just nasty 