All depends what you want in that position.
Been clear from the Winks and Gilmour links that Lampard is looking for someone who can take the ball on the half turn and progress the ball through the lines.
A traditional "holding" player in the Carsley mould (for want of a better example) doesn't give you that, nor does more of a ball winner like Gana.
You look at City who've got Rodri who can do it all, maybe Declan Rice and arguably Phillips. Outside that, you've got specialists in being different types of number 6.
Gilmour gives you someone incredibly comfortable on the ball who is press-resistant and helps move the ball between areas of the pitch, whether that's by carrying the ball or by passing it, or even just recycling it. He absolutely doesn't give you the legs to get all over the pitch and press like a Gana/Kante, he also doesn't give you the defensive nous of a Gareth Barry (again for the want of a better example).
He's basically a "type" of holding midfielder which doesn't necessarily fit with what a lot of posters seem to want, but if you accept that the Winks links were genuine then Gilmour seems to fit pretty well into what Lampard sees as the type of number 6 he wants (remember Lampard played Jorginho as the holding player in a 433 and had Kante as a number 8).
Fwiw, as much as I think Gilmour is a potentially huge prospect, I'm actually not sure we are good enough to get away with playing this way. I understand the thought process behind it, but I can see patience wearing thin when the likes of Gilmour are exposed and overrun by the likes of Joelinton/De Bruyne/Bissouma/*insert strong, athletic midfielder name here*