Why does this weld script rotate the parts?

This script should be welding some parts to the players leg, but for some reason, they rotate! The orientation shouldn't be changing.

Heres a photo of what's happening.

https://twitter.com/ChroNomadics/status/675026434960793600

player = game:GetService('Players').LocalPlayer
PlayerAttire = player.PlayerGui:FindFirstChild("Outfit")

function WeldLeftThigh()

    if PlayerAttire ~= nil then

    local OutfitBottom1 = game.Lighting.OutfitStorage.Bottoms:FindFirstChild(PlayerAttire.OutfitBottom.Value)
    local OutfitBottom = OutfitBottom1.LeftThighComponents:Clone()

    OutfitBottom.Parent = game.Workspace
    local c = OutfitBottom:GetChildren()
        for i=1, #c do
            if c[i].className == "Part" or "Unionoperation" then
                local suitW = Instance.new("Weld")
                suitW.Part0 = OutfitBottom.PrimaryPart
                suitW.Part1 = c[i]
                local autoW = CFrame.new(OutfitBottom.PrimaryPart.Position)
                suitW.C0 = OutfitBottom.PrimaryPart.CFrame:inverse()*autoW
                suitW.C1 = c[i].CFrame:inverse()*autoW
                suitW.Parent = OutfitBottom.PrimaryPart
            end
            local bpW = Instance.new("Weld")
            bpW.Part0 = player.Character["LeftThigh"]
            bpW.Part1 = OutfitBottom.PrimaryPart
            bpW.C0 = CFrame.new(0, 0, 0)
            bpW.Parent = OutfitBottom.PrimaryPart

        end

        local D = OutfitBottom:getChildren()
        for i=1, #D do
            D[i].Anchored = false
            D[i].CanCollide = false
        end
    end
end

while true do
    wait(0.5)
    WeldTop()
    WeldPelvicSection()
    WeldLeftShoulder()
    WeldRightShoulder()
    WeldRightThigh()
    WeldLeftThigh()
    script:Destroy()
end

Thanks.