Not necessarily agreeing with the notion of moving the sniper to T2, but regardless of that, the argument cuts both ways. British infantry sections are only buildable once there are plenty of counters available (MG42, sniper).
Applying this very same logic British Infantry should be given a chance to be on the field for a while before its hard counter is available. Therefore Sniper should come later.
If it's unfair for a Sniper to coexist with Allied light vehicles, then it is unfair for Tommies to coexist with German sniper.
My point is, units are plenty useful once there are counters on the field. The whole idea of usability windows is flawed IMO. A German sniper lasts well into the late game.
A fix is needed. Timing is not it.
On the contrary, I do believe in the window of effectiveness, but in another way. When new, and "better" units arrive, both for you and your enemy, you are gonna be busy microing them and you can't babysit other units, specially fragile units like 222, M20, M3 and... Sniper. But, this is greatly related to your skill level, so an average player like me will completely forget about a sniper and can not micro them effectively. This may or may not be true for you.
I also have to clarify that by this so called window of effectiveness, I mean the period in which you can utilize your units to their full potential, which is both related to your and your enemy's skill. So in our case, you can and should utilize your sniper early in the game, before units like M20 arrive. The arrival of hard counters will make it a lot harder for you to use the unit (Duh, Sherlock). It doesn't mean that the unit is obsolete though, as you stated.
Anyway, I'm not gonna argue and you're entitled to your opinion. All I'm saying is, since Ost sniper is kinda unfair versus Brits, I don't see any problems with moving Brit Sniper to T0. It not possible to spam it, it can counter Kuble rush, and it can be used to counter snipe.