I thought Tali's "I'm mourning a geth line was pretty descriptive and certainly hasn't been anything humorous in how that whole scene plays out in any playtrhough I've done so far. People seem upset enough about being autodialogued... I would have thought they would get more upset into being railroaded into a "full-blown" funeral for it. I do think it would have been nice to have had the option to not mourn Legion at all. I suppose they could have added a datapad from Legion similar to what they did with Mordin.
The fact that she still gets that line even if the "friend" she just "murdered" was the "not Legion" doppelganger for ME2 Legion (that she even called a "thing" a few times just beforehand) serves as a perfect example of how much of a lazy afterthought it was.
The railroading is annoying given how we could approach our relationship to Legion in ME2, but I don't think a little memorial would have made it any worse than it already was. There's already no option to play a Shep who is pro AI technologies, but doesn't think of them as people (ala Admiral Xen or Gavin Archer). If you wanna be an anti AI Luddite, you just never reactivate Legion in ME2, and then you never get railroaded to calling a toaster your "friend", and can even tell the Geth VI to literally go find the airlock when it starts whining, at least (still can do nothing about EDI though).
Reegar just got the shaft in ME3 in general, so that Tali forgets he ever existed at all is unsurprising. He should have appeared somewhere during Rannoch (maybe helping rescue Koris or running another team on the Dreadnought/ Reaper base), not a goddamn Email and a DLC gun, but I imagine a common sympathetic quarian wouldn't have jibed with the rest of the toaster hugging narrative. Given how badly Han'Gerrel got villainized into a ruthless, literal ideological punching bag from his amicable ME2 version, it's probably for the best that whoever was writing Rannoch arc in ME3 didn't put their hands on Reegar and attemt to do something similar.