Colonization of sindar or sindar doing the colonizing? Uh wait, this got long:
Er, I guess if it’s the first, like, idk I have the same opinion as most people? It was presumptive and based on kind of bigoted rationales? Uh, more unpopular. So, yeah the noldor did kind of save the sindar from being destroyed by morgoth and when some of the sindar claim that the noldor are responsible for all the wars and shit in beleriand, that’s objectively untrue – Morgoth would have been just as or more aggressive and destructive if the noldor hadn’t come. On the other hand, like, the noldor pretty transparently are not here solely on some noble selfless rescue mission, they’re here to get revenge and to set up kingdoms of their own where they can rule over other people, and the Sindar are 100% correct when they dislike the noldor for that, even setting the kinslaying aside. Also they have absolutely 0 obligation to help make the noldor’s lives easier by capitulating to them or by helping the noldor do this better based on the specific reasoning that the noldor are doing something about Morgoth and the noldor saved them from Morgoth and helping them equates to doing what’s best for everybody – the noldor have a pretty specific idea about what constitutes victory over Morgoth: somehow “defeating” him by “killing” him or otherwise ridding beleriand of his presence. The sindar have been in Beleriand a hell of a lot longer than the noldor and have a hell of a lot more invested in it, and wow – maybe the people who are natives of a land just might be the foremost authorities on what’s the best way to defend it! Maybe if the noldor were genuinely rationally concerned with defeating Morgoth and saving beleriand above all else, they would lend their military strength and knowledge of Morgoth’s character and of their Valinorian technology and math and lore as A+ consulting support to help the sindar protect their land from Morgoth! What an idea! And the sindar have no reason to think the noldor’s plans are going to work or are in any way a good or helpful strategy. Morgoth isn’t like 3rd age Sauron, who has some specific weak point that can destroy him for good.
Uh, colonization by the sindar: like of eastern ME in the second and third ages, if this is what you meant? Well, first of all, when the sindar talk about “going back to their kin they left behind in ancient times” or whatever, it doesn’t necessarily mean “go back to claim we can plop down in a land among a people we have been estranged from for generations” like it would for humans. Elves are immortal. It can literally mean “lets go crash with Uncle Galion and his family who we haven’t seen in 3,000 years.” Not necessarily of course, but there’s a grey area of possibilities there. Otoh, it’s always amusing when people try to disguise their frothing misogyny by whining about ooOOOOooo Galadriel stole Lothlorien and colonized the silvans etc when the relevant information there is pretty damn explicit that a) the sindarin Amdir and Amroth ruled there for centuries before she and Celeborn either set foot there or took up rule there, b) the silvan people specifically asked Galadriel and Celeborn to take up rule in Lothlorien after Amroth died, and c) No one ever says anything of the like about Oropher or Thranduil, even though (alluding to the first point I made about sindar/silvan kinship) they’re not any more legitimately sindar than Celeborn. Presumably bc people like to assume Celeborn is some kind of meek weenie under his wife’s thumb, even though his characterization in LOTR is as much the opposite as you can get.