Yes, your boat has a L/b of 2.94 and anything under 3.00 could be considered beamy. Anything over 4.00 can be considered narrow.
But the former owner is BS'ing you. Your boat is a normal boat ,assuming it's a monohull
. I do not know the Ranger
28TR. Any boat hit by a gust, even the biggest, widest catmaran will react to the gust and heel over to some degree. And the word is "heel" not "keel over".
"Keel over" is what you do when you are drunk.
If in fact your boat is a Gary Mull designed Ranger 28 it is an old IOR boat and they were famous for being initially tender
and heeling very quickly. Ijn fact due to the IOR they werer designed to be initially tender
to gain an advantagious CGF which was a direct multiplier of 'L".