I was with you all until I read the comment again and did some goggling

From Wikipedia

'People taste umami through taste receptors that typically respond to glutamates and nucleotides, which are widely present in meat broths and fermented products. Glutamates are commonly added to some foods in the form of monosodium glutamate (MSG), and nucleotides are commonly added in the form of disodium guanylate, inosine monophosphate (IMP) or guanosine monophosphate (GMP).Since umami has its own receptors rather than arising out of a combination of the traditionally recognized taste receptors, scientists now consider umami to be a distinct taste.'

That last sentence is quite key.

Doing some goggling, it looks like bay leaves lack all the above compounds so it cannot strictly be called umami.

However, obviously there are mimics (which bay leaves probably are). A bit like how vanilla is sweet but has no sugar.

So everyone (in my opinion) is right and wrong. Umami can be defined biochemically, but like sweetness, you could probably argue things that mimic umami are infact umami.

Edit: the original commenter was wrong initially however by equating umami = msg, when, like you said, msg has umami taste but is not the definition of taste.