Considering your lack of experience with SPAA that have to fight SACLOS ATGMs, I don’t think you can make this claim. Especially because you’ve only played one CAS plane with SACLOS ATGMs (That being the A-4E), and you only managed under half of the KD that the average player on Thunderskill managed with it too (0.9 vs 2.05)
Which would be relevant only if helicopters could fire from their helipad. Which they can’t. The very worst the Sgt York has to deal with are the later Hinds with Sturms, which have a 5km range, which is entirely within the Sgt York’s range. Others, like the very common reserve tier ones like the Z-11 and Scout have 3-3.5km range, which is effectively point blank for the Sgt York.
What possible sacrifices does the Sgt York make in an AA role? Yeah, it can’t hunt tanks consistently, but that’s not the role of an SPAA. Meanwhile, it has the capability of engaging planes that other SPAAs can’t even touch. That’s well worth the tradeoff. Judging SPAA by their tank hunting ability is pointless, especially when the topic of conversation is about how they deal (or don’t) with CAS.
And your M19A1 (with 372 battles played) managed a whopping 0.3 KD against planes. Worse than your performance in the Sgt York.
To be fair, this is no surprise, the M19A1 is not a particularly good vehicle at engaging aircraft. The average player on Thunderskill only manages 0.11. But it doesn’t speak to your godlike ability to clear the skies with SPAA.
And the excuse for lack of planes at the tier doesn’t fly either (unintentional pun). The average KD against planes on Thunderskill for the Sgt York is 1.39, shockingly high for an SPAA and higher than every tier 6 SPAA equipped with IR SAMs.
For reference, the Gepard only manages 0.34. I wouldn’t consider these equal in the SPAA role.
Obligatory disclaimer that Thunderskill isn’t super accurate. However, it’s known to have a bias towards better players (Since only better players will have used the site, thus giving their stats over to them). Thus, the actual KDs for these SPAA is likely much worse than they seem here.