You need a space between the ! and the -. I also put the last close parentheses on a separate line below.
However, not sure if you can actually run Python scripts like that as an alias. What is better is to store the script somewhere and then create an alias that uses the full path to the script file like this (default path for scripts shown):
MyAlias : ! -_RunPythonScript "C:\Users\<your user name>\AppData\Roaming\McNeel\Rhinoceros\7.0\scripts\YourScriptName.py"
By default, that path may already be set in your script editor, in that case you can just use this:
MyAlias : ! -_RunPythonScript "YourScriptName.py"