dotnet build doesn't work when filtered to a supported framework for current SDK

I am wanting to build a project with the .NET Core 2.2 SDK. The project targets .NET Core 3.0 and 2.2. It should work, but instead, it makes me sad.

C:\git\testapps\cpumath>type cpumath.csproj
<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFrameworks>netcoreapp3.0;net472;netcoreapp2.2</TargetFrameworks>
    <RuntimeIdentifiers>win-x64;linux-x64</RuntimeIdentifiers>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.ML.CpuMath" Version="0.11.0" />
  </ItemGroup>

</Project>
C:\git\testapps\cpumath>dotnet build -f netcoreapp2.2
Microsoft (R) Build Engine version 15.9.20+g88f5fadfbe for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

C:\Program Files\dotnet\sdk\2.2.105\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.TargetFrameworkInference.targets(137,5): error NETSDK1045: The current .NET SDK does not support targeting .NET Core 3.0.  Either target .NET Core 2.2 or lower, or use a version of the .NET SDK that supports .NET Core 3.0. [C:\git\testapps\cpumath\cpumath.csproj]

C:\git\testapps\cpumath>dotnet --info
.NET Core SDK (reflecting any global.json):
 Version:   2.2.105
 Commit:    7cecb35b92

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.17763
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\2.2.105\

Host (useful for support):
  Version: 3.0.0-preview4-27529-09
  Commit:  0a688d1b7e

[dsplaisted]

Basically, NuGet restores for all target frameworks even if you specify a given framework to build / publish for. This avoids having to re-restore each time and thrashing the assets file each time you specify a different target framework. So that would be the trade-off if we wanted to enable this scenario.

Note that I think you could do something like what you want by specifying /p:TargetFrameworks=netcoreapp2.2 instead of -f netcoreapp2.2.

[dsplaisted]

We recommend using the latest SDK even for projects targeting earlier runtimes. Probably the instructions for building the TS3AudioBot project weren’t updated when it added .NET Core 3.0 support.

We recommend using the latest SDK because that’s where all of our fixes and improvements go. For example, even if we were to do as you suggest and skip restoring frameworks that aren’t supported, that change would go in a future SDK (ie the .NET 5 SDK or later), and wouldn’t help in the case where the 2.2 SDK was trying to restore assets for .NET Core 3.0.