Toon owner Ashley revealed earlier this week he was planning to try and sell the naming rights to Newcastle's home ground after taking the club off the market.
The news has been met by anger and frustration by Magpies fans and former supremo Shepherd, who sold his stake in the club to Ashley, understands the fury over Ashley's controversial plans.
"I suppose nothing surprises me about the current regime, so news they are ready to sell the naming rights isn't exactly a shock," said Shepherd.
"I appreciate we are living in a commercial world, but there are some things money can't buy.
"St James' Park is one of the most famous stadia, not just in Europe but in the world. You can go anywhere and everyone knows St James' Park is the home of Newcastle United. The two are synonymous.
"I just can't imagine St James' Park being called anything else. Whatever next? Why don't they just go the whole hog and change the name of the club itself?
"Fans will be horrified, angry and upset about this. They've had to put up with a lot in recent months, but this is just another blow."
BrandingShepherd revealed he had rejected an offer of £3million to change the name of St James' Park during his tenure in charge.
"I can remember when we had the chance to change the name of the ground when I was chairman," added Shepherd.
"It was just after flotation and big-name companies were falling over themselves to get involved in football - and back then, Newcastle were right up there with the Manchester Uniteds, Liverpools and Arsenals.
"We were offered something like £3million for a five-year deal. The branding specialists didn't reveal the identity of the interested parties, otherwise we could just have approached the companies direct.
"The money could have been 10-times that and I would still not have been interested. There are some things money can't buy."