Looking at those levels, and noting that level 4+ is pretty rare in skill terms, and level 3 is axiomatically defined as a professional skill level... it would seem to be a good fit, but it makes level 0 in a language somewhat more fluent than I'd care for. I'd instead use 2x level as the ILR or DLI level equivalent. (DLI uses a very similar scale.)
I don't know about DLI, but IMHO as level 0 (as defined in the sidebar in page 51 of the Core Book, as we're in the MgT forum) means he is competent in that skill but has little experience, I see it usable as the ILR 1 as Fox's Master devines in his post, while each level, defined on the same sidebar as several years of experience using that skill, might well be ILR 2, and skill 2 ILR 3, but I don't see it as much as full profesional experience (as Fox's Master defines ILR 4, that would be level x 2) yet, leaving that as Profesional working experience (ILR 3, according to Fox's Master).
Personally, dealing with MgT, I'd keep with the skill +1 as ILR, as Fox's Master defined it. Other Traveller versions may vary, of course.